The document describes the electron transport chain in mitochondria. It has three key points:
1. The electron transport chain consists of four complexes embedded in the inner mitochondrial membrane, along with electron carriers like CoQ, cytochromes, and Fe-S centers that shuttle electrons between the complexes. Complexes I, III, and IV establish a proton gradient by pumping protons out of the matrix.
2. Electrons enter the chain from NADH and FADH2, and are passed through the carriers and complexes until they reach oxygen and are used to form water. This electron transfer is coupled to proton pumping.
3. The proton gradient drives ATP synthase to phosphorylate ADP into ATP,
This document summarizes oxidative phosphorylation (OXPHOS) and the electron transport chain in mitochondria. It states that OXPHOS is essential for generating ATP through the transfer of electrons from donor molecules like NADH to oxygen. It occurs through five protein complexes embedded in the inner mitochondrial membrane: complex I-IV transfer electrons and pump protons out of the matrix, while complex V uses the proton gradient to drive ATP synthesis. The document provides an overview of each complex and how they facilitate electron transfer and proton pumping to create the electrochemical gradient used for ATP production.
This document discusses the electron transport chain (ETC) and its components. It notes that the ETC is located in the inner mitochondrial membrane and utilizes electrons derived from nutrients to generate ATP through a series of oxidation-reduction reactions. It describes the five complexes of the ETC (Complexes I-IV which transport electrons and Complex V which synthesizes ATP) as well as the mobile carriers involved in electron transport, including NADH, Coenzyme Q, cytochrome c, and oxygen. The ETC functions to transfer electrons from substrates to oxygen and harness the energy to produce ATP, making mitochondria the powerhouse of the cell.
Biological oxidation and Electron Transport Chain is the most important and confusing topic in biochemistry metabolism, but here we tried to put it in the simplest way easy to learn. This presentation was guided by Dr. Arpita Patel and made by Miss Nidhi Argade.
This document discusses the biosynthesis of phospholipids. It begins by defining phospholipids as complex lipids containing phosphoric acid, fatty acids, nitrogenous bases, and alcohols. Phospholipids are synthesized primarily on the surfaces of the smooth endoplasmic reticulum and transported via vesicles to their destinations. There are two main types of phospholipids - glycerophospholipids and sphingolipids. Glycerophospholipids have asymmetrical fatty acid groups attached to carbon 1 and 2 of the glycerol backbone. They are synthesized by attaching two fatty acyl groups to glycerol-3-phosphate to form phosphatidic acid. The document then discusses the synthesis of specific phospholipids
Metabolism of Purine & Pyrimidine nucleotideEneutron
This document summarizes the biosynthesis pathways of purine and pyrimidine nucleotides. It discusses:
1) Purine biosynthesis occurs in two phases - first the synthesis of aminoimidazole ribosyl-5-phosphate (VII) from ribose 5-phosphate, then the synthesis of inosine monophosphate (IMP, XII) from aminoimidazole ribosyl-5-phosphate.
2) Pyrimidine biosynthesis differs in that the pyrimidine ring is first synthesized, followed by attachment to ribose phosphate. It begins with carbamoyl phosphate and involves intermediates like orotic acid and orotidylate before forming uridine monophosph
Fungal fatty acid synthase (FAS) has a barrel shape with a central wheel that divides it into two reaction chambers. Catalytic domains are distributed across two polypeptide chains, with the alpha chain forming the central wheel and beta chains forming the arms. In comparison, mammalian FAS is a single chain that integrates all catalytic steps. While fungal and mammalian FAS differ in structure, both animals and fungi possess Type I FAS where all steps of fatty acid synthesis are contained within a multi-enzyme complex.
The document summarizes cellular respiration and the production of ATP through oxidative phosphorylation. It discusses how carbohydrates, fats, and amino acids are broken down to feed into the electron transport chain, whose purpose is to release energy to drive the synthesis of ATP from ADP and inorganic phosphate. The process occurs within the inner mitochondrial membrane in complexes of the electron transport chain, and generates more ATP per pair of electrons carried through when NADH is oxidized compared to FADH2. The availability of ADP regulates the rate of ATP production. Oxygen consumption and ADP levels increase under conditions when ATP is needed at a rapid rate, such as during exercise. Some physiological and synthetic uncoupling agents can disrupt this phosphorylation process
The document summarizes electron transport and oxidative phosphorylation. It describes how electrons from NADH and FADH2 are transported via carriers in the mitochondrial electron transport system to oxygen, with energy released used to synthesize ATP. Protons are pumped from the mitochondrial matrix to the intermembrane space, building a proton gradient that drives ATP synthesis by ATP synthase as protons flow back into the matrix. This chemiosmotic coupling allows efficient conversion of electron potential energy to chemical energy in the form of ATP.
This document summarizes oxidative phosphorylation (OXPHOS) and the electron transport chain in mitochondria. It states that OXPHOS is essential for generating ATP through the transfer of electrons from donor molecules like NADH to oxygen. It occurs through five protein complexes embedded in the inner mitochondrial membrane: complex I-IV transfer electrons and pump protons out of the matrix, while complex V uses the proton gradient to drive ATP synthesis. The document provides an overview of each complex and how they facilitate electron transfer and proton pumping to create the electrochemical gradient used for ATP production.
This document discusses the electron transport chain (ETC) and its components. It notes that the ETC is located in the inner mitochondrial membrane and utilizes electrons derived from nutrients to generate ATP through a series of oxidation-reduction reactions. It describes the five complexes of the ETC (Complexes I-IV which transport electrons and Complex V which synthesizes ATP) as well as the mobile carriers involved in electron transport, including NADH, Coenzyme Q, cytochrome c, and oxygen. The ETC functions to transfer electrons from substrates to oxygen and harness the energy to produce ATP, making mitochondria the powerhouse of the cell.
Biological oxidation and Electron Transport Chain is the most important and confusing topic in biochemistry metabolism, but here we tried to put it in the simplest way easy to learn. This presentation was guided by Dr. Arpita Patel and made by Miss Nidhi Argade.
This document discusses the biosynthesis of phospholipids. It begins by defining phospholipids as complex lipids containing phosphoric acid, fatty acids, nitrogenous bases, and alcohols. Phospholipids are synthesized primarily on the surfaces of the smooth endoplasmic reticulum and transported via vesicles to their destinations. There are two main types of phospholipids - glycerophospholipids and sphingolipids. Glycerophospholipids have asymmetrical fatty acid groups attached to carbon 1 and 2 of the glycerol backbone. They are synthesized by attaching two fatty acyl groups to glycerol-3-phosphate to form phosphatidic acid. The document then discusses the synthesis of specific phospholipids
Metabolism of Purine & Pyrimidine nucleotideEneutron
This document summarizes the biosynthesis pathways of purine and pyrimidine nucleotides. It discusses:
1) Purine biosynthesis occurs in two phases - first the synthesis of aminoimidazole ribosyl-5-phosphate (VII) from ribose 5-phosphate, then the synthesis of inosine monophosphate (IMP, XII) from aminoimidazole ribosyl-5-phosphate.
2) Pyrimidine biosynthesis differs in that the pyrimidine ring is first synthesized, followed by attachment to ribose phosphate. It begins with carbamoyl phosphate and involves intermediates like orotic acid and orotidylate before forming uridine monophosph
Fungal fatty acid synthase (FAS) has a barrel shape with a central wheel that divides it into two reaction chambers. Catalytic domains are distributed across two polypeptide chains, with the alpha chain forming the central wheel and beta chains forming the arms. In comparison, mammalian FAS is a single chain that integrates all catalytic steps. While fungal and mammalian FAS differ in structure, both animals and fungi possess Type I FAS where all steps of fatty acid synthesis are contained within a multi-enzyme complex.
The document summarizes cellular respiration and the production of ATP through oxidative phosphorylation. It discusses how carbohydrates, fats, and amino acids are broken down to feed into the electron transport chain, whose purpose is to release energy to drive the synthesis of ATP from ADP and inorganic phosphate. The process occurs within the inner mitochondrial membrane in complexes of the electron transport chain, and generates more ATP per pair of electrons carried through when NADH is oxidized compared to FADH2. The availability of ADP regulates the rate of ATP production. Oxygen consumption and ADP levels increase under conditions when ATP is needed at a rapid rate, such as during exercise. Some physiological and synthetic uncoupling agents can disrupt this phosphorylation process
The document summarizes electron transport and oxidative phosphorylation. It describes how electrons from NADH and FADH2 are transported via carriers in the mitochondrial electron transport system to oxygen, with energy released used to synthesize ATP. Protons are pumped from the mitochondrial matrix to the intermembrane space, building a proton gradient that drives ATP synthesis by ATP synthase as protons flow back into the matrix. This chemiosmotic coupling allows efficient conversion of electron potential energy to chemical energy in the form of ATP.
This document summarizes the biosynthesis of amino acids from key metabolic precursors. It discusses 6 families of amino acid biosynthesis defined by their precursor: (1) α-ketoglutarate family (glutamate, glutamine, proline, arginine), (2) 3-phosphoglycerate family (serine, glycine, cysteine), (3) oxaloacetate family (aspartate, asparagine, methionine, threonine, lysine), (4) pyruvate family (alanine, valine, leucine, isoleucine), (5) phosphoenolpyruvate and erythrose 4-phosphate family (tryptoph
As an essential amino acid, methionine is not synthesized de novo in humans and other animals, which must ingest methionine or methionine-containing proteins. In plants and microorganisms, methionine biosynthesis belongs to the aspartate family, along with threonine and lysine (via diaminopimelate, but not via α-aminoadipate). The main backbone is derived from aspartic acid, while the sulfur may come from cysteine, methanethiol, or hydrogen sulfide.
The document summarizes the Krebs cycle, also known as the citric acid cycle or TCA cycle. It describes the cycle as a series of reactions that occur in mitochondria resulting in the oxidation of acetyl CoA to produce carbon dioxide, hydrogen atoms, and high-energy electron carriers. The cycle contains 8 enzyme-mediated steps that ultimately generate 3 NADH molecules, 1 FADH2, 1 GTP/ATP, and 2 CO2 per turn of the cycle. The cycle plays a key role in aerobic respiration by generating electron carriers that feed into the electron transport chain to produce ATP.
The document discusses biological oxidation and energy production in cells. It can be summarized as:
i. Biological oxidation involves the transfer of electrons from nutrients through an electron transport chain (ETC) in the mitochondria to oxygen. This releases energy that is trapped as ATP through oxidative phosphorylation.
ii. The ETC consists of four complexes embedded in the inner mitochondrial membrane that sequentially accept electrons from electron carriers like NADH and FADH2. As electrons flow through the complexes, protons are pumped from the matrix to the intermembrane space.
iii. The proton gradient drives ATP synthase to phosphorylate ADP to ATP. This couples oxidation of nutrients to phosphorylation in the mitochondria to produce cellular energy through
oxidation of alpha, beta fatty acid and unsaturated fatty acid mariagul6
This document summarizes fatty acid oxidation through beta-oxidation. It discusses how fatty acids are broken down into acetyl-CoA in the mitochondria, generating energy in the form of ATP. Key points covered include the carnitine shuttle transport system, reactions of beta-oxidation, and oxidation of odd-chain and unsaturated fatty acids. Deficiencies in carnitine or the carnitine shuttle enzymes can impair fatty acid breakdown.
The citric acid cycle (also known as the Krebs cycle or TCA cycle) is a series of oxidation-reduction reactions in mitochondria that oxidizes acetyl groups and reduces coenzymes, which are then reoxidized to generate ATP. The cycle takes place in the mitochondrial matrix and is the primary step of aerobic processing in eukaryotic cells. It oxidizes glucose, fatty acids, and amino acids to carbon dioxide while collecting electrons to produce NADH and FADH2, which power the electron transport chain to generate ATP. The cycle was discovered by Hans Krebs in 1937 and is the central metabolic hub of the cell.
This document discusses fatty acid synthesis in the body. It begins by defining fatty acids and describing their roles in energy storage and as structural components of membranes. There are three systems for fatty acid synthesis: de novo synthesis in the cytoplasm, chain elongation in mitochondria, and chain elongation in microsomes. De novo synthesis occurs primarily in the liver and adipose tissues, starting from acetyl-CoA derived from glucose. This synthesis takes place in the cytoplasm and requires acetyl-CoA transport from mitochondria via citrate. The document then details the multi-step process of de novo fatty acid synthesis catalyzed by acetyl-CoA carboxylase and fatty acid synthase, and describes regulation of synthesis by products, hormones,
The document summarizes the organization of the mitochondrial electron transport chain. It describes the five complexes of the electron transport chain (Complexes I-V), including their components, functions, and electron transfer processes. Specifically, it details how Complexes I, III, and IV transfer electrons from donors like NADH to final acceptors like oxygen. This generates a proton gradient across the inner mitochondrial membrane, which Complex V then uses to synthesize ATP through oxidative phosphorylation.
The electron transport chain is comprised of a series of enzymatic reactions within the inner membrane of the mitochondria, which are cell organelles that release and store energy for all physiological needs.
As electrons are passed through the chain by a series of oxidation-reduction reactions, energy is released, creating a gradient of hydrogen ions, or protons, across the membrane. The proton gradient provides energy to make ATP, which is used in oxidative phosphorylation.
The document summarizes electron transport chain (ETC) and ATP synthase. It describes:
1) ETC consists of 5 complexes (I-IV and V) in the mitochondria that transport electrons from nutrients to oxygen, pumping protons out and building up a proton gradient.
2) Complexes I, III, and IV pump protons out while Complex V (ATP synthase) uses the proton gradient to phosphorylate ADP, producing ATP.
3) Electrons are passed through complexes via electron carriers like NADH, FADH2, and cytochromes while protons are pumped from the matrix to the intermembrane space.
Biosynthesis of pyrimidine nucleotides can occur by a de novo pathway or by the reutilization of preformed pyrimidine bases or ribonucleosides (salvage pathway).
The pyrimidine synthesis is a similar process than that of purines. In the de novo synthesis of pyrimidines, the ring is synthesized first and then it is attached to a ribose-phosphate to for a pyrimidine nucleotide.
1. Biological oxidation is the cellular process by which organic substances like carbohydrates, fats, and proteins release energy through redox reactions, producing CO2, H2O, and ATP.
2. In the mitochondria, electrons are transferred through redox carriers in the electron transport chain from NADH or FADH2 to oxygen, driving the pumping of protons across the inner mitochondrial membrane and building an electrochemical gradient.
3. The potential energy of this proton gradient is harnessed by ATP synthase to phosphorylate ADP, coupling electron transport to oxidative phosphorylation and the production of ATP through chemiosmosis.
Biological oxidation involves the loss of electrons and/or hydrogen atoms from a molecule through enzymatic reactions. There are three classes of biological oxidation: loss of electrons, loss of hydrogen atoms, or addition of oxygen atoms. During electron transport chain reactions, electrons from energy-rich molecules are transferred through electron carriers like NADH and FADH2 to oxygen. This releases free energy used to generate a proton gradient across the inner mitochondrial membrane and to synthesize ATP through oxidative phosphorylation. ATP acts as an energy currency by transferring phosphate groups from energy-rich intermediates to ADP.
Nucleotide metabolism (purine and pyrimidine synthesis)Areeba Ghayas
NUCLEOTIDE METABOLISM,DE NOVO SYNTHESIS OF PURINE, SALVAGE PATHWAY OF PURINE, DE-NOVO SYNTHESIS OF PYRIMIDINE, SALVAGE PATHWAY OF PYRIMIDINE, GOUT, HYPERURICEMIA, LESCH-NYAN SYNDROME, OROTIC ACIDURIA
Biological oxidation involves the transfer of electrons, with oxidation being the removal of electrons and reduction being the gain of electrons. Higher life forms rely completely on oxygen for life processes like respiration, where cells derive energy from the reaction of hydrogen and oxygen to produce water. However, many reactions in living systems occur without oxygen involvement, catalyzed by dehydrogenases. Oxygen is also required to treat respiratory and cardiac failure. Redox reactions can be expressed as half reactions with a reducing agent donating electrons and an oxidizing agent accepting electrons. The redox potential measures a substance's affinity for electrons. Enzymes involved in redox reactions include oxidases, dehydrogenases, hydroperoxidases, and oxygenases.
This document summarizes the biosynthesis of various amino acids from different metabolic precursors. It discusses 6 main families of amino acid biosynthesis defined by their precursor: (1) α-ketoglutarate family including glutamate, glutamine, proline, and arginine; (2) 3-phosphoglycerate family including serine, glycine, and cysteine; (3) oxaloacetate family including aspartate, asparagine, methionine, threonine, and lysine; (4) pyruvate family including alanine, valine, leucine, and isoleucine; (5) phosphoenolpyruvate and erythrose 4-phosphate
Electron Transport Chain and oxidative phosphorylationusmanzafar66
The electron transport chain (ETC) transfers electrons through protein complexes in membranes to create a proton gradient. This gradient drives ATP synthase to make ATP from ADP + Pi. The ETC couples electron transfer to proton pumping across the membrane. In mitochondria, electrons come from NADH/FADH2 and are transferred through Complexes I-IV to oxygen, pumping protons. This creates a gradient to power ATP synthase and make ATP through oxidative phosphorylation. Uncouplers disrupt this coupling to generate heat instead of ATP. The ETC is important in both aerobic respiration and photosynthesis.
1. Beta-oxidation is the major pathway for fatty acid oxidation that occurs in the mitochondria. It involves activation of fatty acids to acyl-CoA derivatives, transport into the mitochondria, and four steps of beta-oxidation to sequentially cleave two-carbon acetyl-CoA units, producing ATP.
2. Minor pathways include alpha-oxidation of phytanic acid in peroxisomes, omega-oxidation of fatty acids in the ER, and peroxisomal beta-oxidation of very long chain fatty acids.
3. Defects in these pathways can cause diseases like Refsum's disease and Zellweger syndrome. Medium chain acyl-CoA
1. Biological oxidation involves the transfer of electrons between electron donors and electron acceptors. This transfer is facilitated by enzymes called oxidoreductases.
2. The electron transport chain is a series of complexes embedded in the mitochondrial inner membrane that transfers electrons from electron carriers like NADH and FADH2 through a series of redox reactions utilizing carriers like ubiquinone and cytochromes.
3. As electrons are transferred through the electron transport chain complexes, protons are pumped from the mitochondrial matrix to the intermembrane space, creating an electrochemical gradient that drives the synthesis of ATP by ATP synthase utilizing oxidative phosphorylation.
This document summarizes the biosynthesis of amino acids from key metabolic precursors. It discusses 6 families of amino acid biosynthesis defined by their precursor: (1) α-ketoglutarate family (glutamate, glutamine, proline, arginine), (2) 3-phosphoglycerate family (serine, glycine, cysteine), (3) oxaloacetate family (aspartate, asparagine, methionine, threonine, lysine), (4) pyruvate family (alanine, valine, leucine, isoleucine), (5) phosphoenolpyruvate and erythrose 4-phosphate family (tryptoph
As an essential amino acid, methionine is not synthesized de novo in humans and other animals, which must ingest methionine or methionine-containing proteins. In plants and microorganisms, methionine biosynthesis belongs to the aspartate family, along with threonine and lysine (via diaminopimelate, but not via α-aminoadipate). The main backbone is derived from aspartic acid, while the sulfur may come from cysteine, methanethiol, or hydrogen sulfide.
The document summarizes the Krebs cycle, also known as the citric acid cycle or TCA cycle. It describes the cycle as a series of reactions that occur in mitochondria resulting in the oxidation of acetyl CoA to produce carbon dioxide, hydrogen atoms, and high-energy electron carriers. The cycle contains 8 enzyme-mediated steps that ultimately generate 3 NADH molecules, 1 FADH2, 1 GTP/ATP, and 2 CO2 per turn of the cycle. The cycle plays a key role in aerobic respiration by generating electron carriers that feed into the electron transport chain to produce ATP.
The document discusses biological oxidation and energy production in cells. It can be summarized as:
i. Biological oxidation involves the transfer of electrons from nutrients through an electron transport chain (ETC) in the mitochondria to oxygen. This releases energy that is trapped as ATP through oxidative phosphorylation.
ii. The ETC consists of four complexes embedded in the inner mitochondrial membrane that sequentially accept electrons from electron carriers like NADH and FADH2. As electrons flow through the complexes, protons are pumped from the matrix to the intermembrane space.
iii. The proton gradient drives ATP synthase to phosphorylate ADP to ATP. This couples oxidation of nutrients to phosphorylation in the mitochondria to produce cellular energy through
oxidation of alpha, beta fatty acid and unsaturated fatty acid mariagul6
This document summarizes fatty acid oxidation through beta-oxidation. It discusses how fatty acids are broken down into acetyl-CoA in the mitochondria, generating energy in the form of ATP. Key points covered include the carnitine shuttle transport system, reactions of beta-oxidation, and oxidation of odd-chain and unsaturated fatty acids. Deficiencies in carnitine or the carnitine shuttle enzymes can impair fatty acid breakdown.
The citric acid cycle (also known as the Krebs cycle or TCA cycle) is a series of oxidation-reduction reactions in mitochondria that oxidizes acetyl groups and reduces coenzymes, which are then reoxidized to generate ATP. The cycle takes place in the mitochondrial matrix and is the primary step of aerobic processing in eukaryotic cells. It oxidizes glucose, fatty acids, and amino acids to carbon dioxide while collecting electrons to produce NADH and FADH2, which power the electron transport chain to generate ATP. The cycle was discovered by Hans Krebs in 1937 and is the central metabolic hub of the cell.
This document discusses fatty acid synthesis in the body. It begins by defining fatty acids and describing their roles in energy storage and as structural components of membranes. There are three systems for fatty acid synthesis: de novo synthesis in the cytoplasm, chain elongation in mitochondria, and chain elongation in microsomes. De novo synthesis occurs primarily in the liver and adipose tissues, starting from acetyl-CoA derived from glucose. This synthesis takes place in the cytoplasm and requires acetyl-CoA transport from mitochondria via citrate. The document then details the multi-step process of de novo fatty acid synthesis catalyzed by acetyl-CoA carboxylase and fatty acid synthase, and describes regulation of synthesis by products, hormones,
The document summarizes the organization of the mitochondrial electron transport chain. It describes the five complexes of the electron transport chain (Complexes I-V), including their components, functions, and electron transfer processes. Specifically, it details how Complexes I, III, and IV transfer electrons from donors like NADH to final acceptors like oxygen. This generates a proton gradient across the inner mitochondrial membrane, which Complex V then uses to synthesize ATP through oxidative phosphorylation.
The electron transport chain is comprised of a series of enzymatic reactions within the inner membrane of the mitochondria, which are cell organelles that release and store energy for all physiological needs.
As electrons are passed through the chain by a series of oxidation-reduction reactions, energy is released, creating a gradient of hydrogen ions, or protons, across the membrane. The proton gradient provides energy to make ATP, which is used in oxidative phosphorylation.
The document summarizes electron transport chain (ETC) and ATP synthase. It describes:
1) ETC consists of 5 complexes (I-IV and V) in the mitochondria that transport electrons from nutrients to oxygen, pumping protons out and building up a proton gradient.
2) Complexes I, III, and IV pump protons out while Complex V (ATP synthase) uses the proton gradient to phosphorylate ADP, producing ATP.
3) Electrons are passed through complexes via electron carriers like NADH, FADH2, and cytochromes while protons are pumped from the matrix to the intermembrane space.
Biosynthesis of pyrimidine nucleotides can occur by a de novo pathway or by the reutilization of preformed pyrimidine bases or ribonucleosides (salvage pathway).
The pyrimidine synthesis is a similar process than that of purines. In the de novo synthesis of pyrimidines, the ring is synthesized first and then it is attached to a ribose-phosphate to for a pyrimidine nucleotide.
1. Biological oxidation is the cellular process by which organic substances like carbohydrates, fats, and proteins release energy through redox reactions, producing CO2, H2O, and ATP.
2. In the mitochondria, electrons are transferred through redox carriers in the electron transport chain from NADH or FADH2 to oxygen, driving the pumping of protons across the inner mitochondrial membrane and building an electrochemical gradient.
3. The potential energy of this proton gradient is harnessed by ATP synthase to phosphorylate ADP, coupling electron transport to oxidative phosphorylation and the production of ATP through chemiosmosis.
Biological oxidation involves the loss of electrons and/or hydrogen atoms from a molecule through enzymatic reactions. There are three classes of biological oxidation: loss of electrons, loss of hydrogen atoms, or addition of oxygen atoms. During electron transport chain reactions, electrons from energy-rich molecules are transferred through electron carriers like NADH and FADH2 to oxygen. This releases free energy used to generate a proton gradient across the inner mitochondrial membrane and to synthesize ATP through oxidative phosphorylation. ATP acts as an energy currency by transferring phosphate groups from energy-rich intermediates to ADP.
Nucleotide metabolism (purine and pyrimidine synthesis)Areeba Ghayas
NUCLEOTIDE METABOLISM,DE NOVO SYNTHESIS OF PURINE, SALVAGE PATHWAY OF PURINE, DE-NOVO SYNTHESIS OF PYRIMIDINE, SALVAGE PATHWAY OF PYRIMIDINE, GOUT, HYPERURICEMIA, LESCH-NYAN SYNDROME, OROTIC ACIDURIA
Biological oxidation involves the transfer of electrons, with oxidation being the removal of electrons and reduction being the gain of electrons. Higher life forms rely completely on oxygen for life processes like respiration, where cells derive energy from the reaction of hydrogen and oxygen to produce water. However, many reactions in living systems occur without oxygen involvement, catalyzed by dehydrogenases. Oxygen is also required to treat respiratory and cardiac failure. Redox reactions can be expressed as half reactions with a reducing agent donating electrons and an oxidizing agent accepting electrons. The redox potential measures a substance's affinity for electrons. Enzymes involved in redox reactions include oxidases, dehydrogenases, hydroperoxidases, and oxygenases.
This document summarizes the biosynthesis of various amino acids from different metabolic precursors. It discusses 6 main families of amino acid biosynthesis defined by their precursor: (1) α-ketoglutarate family including glutamate, glutamine, proline, and arginine; (2) 3-phosphoglycerate family including serine, glycine, and cysteine; (3) oxaloacetate family including aspartate, asparagine, methionine, threonine, and lysine; (4) pyruvate family including alanine, valine, leucine, and isoleucine; (5) phosphoenolpyruvate and erythrose 4-phosphate
Electron Transport Chain and oxidative phosphorylationusmanzafar66
The electron transport chain (ETC) transfers electrons through protein complexes in membranes to create a proton gradient. This gradient drives ATP synthase to make ATP from ADP + Pi. The ETC couples electron transfer to proton pumping across the membrane. In mitochondria, electrons come from NADH/FADH2 and are transferred through Complexes I-IV to oxygen, pumping protons. This creates a gradient to power ATP synthase and make ATP through oxidative phosphorylation. Uncouplers disrupt this coupling to generate heat instead of ATP. The ETC is important in both aerobic respiration and photosynthesis.
1. Beta-oxidation is the major pathway for fatty acid oxidation that occurs in the mitochondria. It involves activation of fatty acids to acyl-CoA derivatives, transport into the mitochondria, and four steps of beta-oxidation to sequentially cleave two-carbon acetyl-CoA units, producing ATP.
2. Minor pathways include alpha-oxidation of phytanic acid in peroxisomes, omega-oxidation of fatty acids in the ER, and peroxisomal beta-oxidation of very long chain fatty acids.
3. Defects in these pathways can cause diseases like Refsum's disease and Zellweger syndrome. Medium chain acyl-CoA
1. Biological oxidation involves the transfer of electrons between electron donors and electron acceptors. This transfer is facilitated by enzymes called oxidoreductases.
2. The electron transport chain is a series of complexes embedded in the mitochondrial inner membrane that transfers electrons from electron carriers like NADH and FADH2 through a series of redox reactions utilizing carriers like ubiquinone and cytochromes.
3. As electrons are transferred through the electron transport chain complexes, protons are pumped from the mitochondrial matrix to the intermembrane space, creating an electrochemical gradient that drives the synthesis of ATP by ATP synthase utilizing oxidative phosphorylation.
1. Biological oxidation involves the transfer of electrons between electron donors and electron acceptors. This transfer is facilitated by enzymes called oxidoreductases.
2. The electron transport chain is a series of complexes embedded in the mitochondrial inner membrane that transfers electrons from electron carriers like NADH and FADH2 through a series of redox reactions utilizing carriers like ubiquinone and cytochromes.
3. As electrons are transferred through the complexes of the electron transport chain, protons are pumped from the mitochondrial matrix to the intermembrane space, creating an electrochemical gradient that drives the synthesis of ATP by ATP synthase.
The document discusses the electron transport chain (ETC) in mitochondria. It describes the components and organization of the ETC, including the five protein complexes and electron carriers like NADH, FADH2, coenzyme Q, and cytochromes. The ETC transports electrons from donors like NADH to final acceptors like oxygen, pumping protons across the inner mitochondrial membrane. This generates a proton gradient used by ATP synthase to produce ATP through oxidative phosphorylation, with typically 3 ATP produced per NADH oxidized.
Biological oxidation is the process by which organic substrates are oxidized within living organisms. During this process, oxygen is consumed and carbon dioxide and water are produced, along with the release of energy in the form of ATP or heat. The mitochondria contain four protein complexes - Complexes I to IV - that make up the electron transport chain, through which electrons are transferred from electron donors like NADH to final electron acceptors like oxygen. As electrons are passed through the complexes, protons are pumped from the mitochondrial matrix to the intermembrane space, creating an electrochemical gradient that drives ATP synthesis. While biological oxidation and combustion share similarities in their consumption of oxygen and production of carbon dioxide and water, biological oxidation occurs under controlled conditions with
Electron Transport and Oxidative PhosphorylationHamid Ur-Rahman
The document summarizes electron transport and oxidative phosphorylation in mitochondria. It describes how:
1) The electron transport chain in the inner mitochondrial membrane is made up of four complexes that transfer electrons from nutrients to oxygen, pumping protons from the matrix to the intermembrane space.
2) As electrons are passed through the complexes, energy is used to transport protons against their concentration gradient, building up a electrochemical proton gradient across the inner membrane.
3) ATP synthase uses the potential energy in this proton gradient to phosphorylate ADP, producing ATP through oxidative phosphorylation.
This document provides an overview of oxidative phosphorylation and electron transport chain in mitochondria. It discusses:
1) The chemiosmotic theory proposed by Peter Mitchell which explains how the transport of electrons through the respiratory chain is utilized to produce ATP from ADP and Pi. Proton pumping by Complexes I, III, and IV generates an electrochemical gradient used by ATP synthase.
2) The components of the electron transport chain, including NADH dehydrogenase, succinate dehydrogenase, ubiquinone, cytochromes, and oxygen, arranged in order of increasing redox potential.
3) The four complexes of the electron transport chain - Complexes I-IV - and their roles in proton pumping and
1) Oxidative phosphorylation uses electron transport chain complexes in the mitochondrial inner membrane to generate ATP from ADP and inorganic phosphate. As electrons are passed through Complexes I-IV, protons are pumped from the matrix to the intermembrane space, building an electrochemical gradient.
2) Protons flow back through ATP synthase, driving the phosphorylation of ADP to ATP in the matrix. The electron carriers, including ubiquinone and cytochrome c, shuttle electrons and protons between the complexes.
3) Oxygen is the final electron acceptor, being reduced to water along with protons in Complex IV. This chemiosmotic mechanism couples electron transport to ATP synthesis via the proton gradient across the inner mitochondrial membrane
The electron transport chain is the final pathway where electrons from nutrients are transferred to oxygen to form water. Electrons enter the chain from NADH or FADH2 and are passed through four complexes and coenzyme Q, which pump protons out of the mitochondrial matrix. This creates a proton gradient that is used by ATP synthase to phosphorylate ADP and make ATP via oxidative phosphorylation. The chemiosmotic hypothesis explains this coupling of electron transport to ATP synthesis.
The document discusses the electron transport chain and oxidative phosphorylation. It describes how electrons from nutrients are transferred through enzyme complexes in the mitochondrial membrane to generate a proton gradient. This gradient is then used by ATP synthase to phosphorylate ADP into ATP through oxidative phosphorylation. Inhibitors of the electron transport chain like cyanide and antimycin A prevent this process, while uncouplers allow electron transport without phosphorylation.
The electron transport chain (ETC) transports electrons from electron donors like NADH to molecular oxygen. It consists of protein complexes embedded in the inner mitochondrial membrane. Complexes I, III, and IV pump protons out of the matrix, building up an electrochemical gradient used for ATP synthesis. Electrons flow from complex to complex via mobile carriers like coenzyme Q and cytochrome c. This transfers energy from electrons to protons, conserving energy as ATP. Mitochondria contain many copies of the ETC to generate sufficient ATP through oxidative phosphorylation.
The document discusses the electron transport chain (ETC) in mitochondria. It describes the ETC as a series of electron carriers embedded in the inner mitochondrial membrane that transfers electrons from NADH and FADH2 to oxygen. These carriers include nicotinamide nucleotides, flavoproteins, iron-sulfur proteins, coenzyme Q, and cytochromes. The passage of electrons through this chain is coupled to the pumping of protons across the membrane and generation of ATP by ATP synthase. The document also lists some inhibitors that block electron transport at specific sites in the chain such as rotenone, antimycin A, and cyanide.
Photosystem I is located in the membrane of cyanobacteria and plants. It contains proteins, chlorophylls, carotenoids, and other cofactors that transfer electrons during photosynthesis. PsaA and PsaB form the core where primary electron transfer occurs. Electrons are transferred from P700 to ferredoxin via a chain containing chlorophyll, phylloquinone, and iron-sulfur clusters. Ferredoxin then transfers electrons to ferredoxin-NADP+ reductase to reduce NADP+ to NADPH, providing energy for the Calvin cycle.
This document summarizes electron transport and oxidative phosphorylation. It describes the four complexes of the electron transport chain located in the inner mitochondrial membrane that transport electrons from NADH and FADH2 to oxygen via redox reactions, pumping protons from the matrix to the intermembrane space. This generates a proton gradient that is used by ATP synthase to phosphorylate ADP to ATP, coupling electron transport to oxidative phosphorylation. The chemiosmotic theory of Peter Mitchell is explained, where the proton gradient provides the energy to drive ATP synthesis.
Electron Transport Chain by Salman SaeedSalman Saeed
Electron Transport Chain lecture for Biology, Botany, Zoolog
y, and Chemistry Students by Salman Saeed lecturer Botany University College of Management and Sciences Khanewal, Pakistan.
About Author: Salman Saeed
Qualification: M.SC (Botany), M. Phil (Biotechnology) from BZU Multan.
M. Ed & B. Ed from GCU Faisalabad, Pakistan.
ETS.pptx Govt Nehru PG collage by SOMESH KUMARSOMESH Kumar
The document provides an overview of electron transport chain. It discusses the history, location, components and complexes of ETC. The key components include NADH, FADH2, ubiquinone, cytochromes and ATP synthase. Electrons from NADH and FADH2 are passed through these components via redox reactions to ultimately synthesize ATP. As electrons are passed through complexes I-IV, protons are pumped from the matrix into the intermembrane space, creating an electrochemical gradient used by ATP synthase to phosphorylate ADP.
1. The electron transport chain transfers electrons from electron donors like NADH to electron acceptors like oxygen. This process pumps protons across the inner mitochondrial membrane, creating an electrochemical gradient.
2. Oxidative phosphorylation couples the electron transport chain to ATP synthase. As protons diffuse back into the matrix through ATP synthase, this drives the production of ATP from ADP and inorganic phosphate.
3. The electron transport chain consists of four protein complexes along the inner mitochondrial membrane and two shuttle systems to transfer electrons from the cytoplasm. As electrons are passed from one complex to another, protons are pumped from the matrix to the intermembrane space.
ETC and Phosphorylation by Salman SaeedSalman Saeed
ETC and Phosphorylation lecture for Biology, Botany, Zoology, and Chemistry Students by Salman Saeed lecturer Botany University College of Management and Sciences Khanewal, Pakistan.
About Author: Salman Saeed
Qualification: M.SC (Botany), M. Phil (Biotechnology) from BZU Multan.
M. Ed & B. Ed from GCU Faisalabad, Pakistan.
AnswerThe order of electron movement in the electron transport sy.pdfanurag1231
Answer:
The order of electron movement in the electron transport system:
NADH ---> Complex I ---> Coenzyme Q ---> Complex III ---> Cytochrome C ---> Complex IV
---> O2
Mitochondrial chemiosmosis (through Fernadez Moran inner mitochondrial oxysomes particles)
during cellular respiration obtain energy from chemical enzymatic breakdown of the organic
food molecules (glucose, pyruvate, acetylcoA) to produce ATP. Every 3 protons used to produce
one ATP molecule. Inner membrane possess small protein channels known as porins in
mitochondria & these channels promote the movement of any small molecules such as ATP
through them
Cytochrome c-oxidase associated with two heme groups, one cytochrome a, another cytochrome
a3 along with divalent copper centers (CuA, CuB). This is an integral membrane protein located
specifically in mitochondria of eukaryotes to perform electron transport for the synthesis of
energy in the form of ATP.
Coenzyme Q – cytochrome c oxidoreductase (EC 1.10.2.2) is present in mitochondria. This
enzyme is essential for oxidative phosphorylation during electron transport to generate ATP.
This enzyme complex is “oxidoreductase” type of enzymatic multisubunit transmembrane
protein. The prosthetic groups of this protein are tightly bound non-protein molecules such as
cytochrome B, cytochrome C1, NAD, FAD and other cofactors & these are useful in mediating
catalysis and electron transfer during ATP production
Directions of electron transfer in mitochondria is from NADH---> Complex I --> coenzyme Q --
> complex III ---> cytochrome c ---> Complex IV finally oxygen acceptor.
Proton pump in electron transport chain takes place from Complex I which pumps considerably 4
protons (H+), whereas Complex III pumps nearly 4 protons (H+) finally Complex IV that pumps
out two protons.
Net input in oxidative phosphorylation ----> NADH, ADP, O2, and net output in oxidative
phosphorylation ----------> ATP, NAD+ and Water
Solution
Answer:
The order of electron movement in the electron transport system:
NADH ---> Complex I ---> Coenzyme Q ---> Complex III ---> Cytochrome C ---> Complex IV
---> O2
Mitochondrial chemiosmosis (through Fernadez Moran inner mitochondrial oxysomes particles)
during cellular respiration obtain energy from chemical enzymatic breakdown of the organic
food molecules (glucose, pyruvate, acetylcoA) to produce ATP. Every 3 protons used to produce
one ATP molecule. Inner membrane possess small protein channels known as porins in
mitochondria & these channels promote the movement of any small molecules such as ATP
through them
Cytochrome c-oxidase associated with two heme groups, one cytochrome a, another cytochrome
a3 along with divalent copper centers (CuA, CuB). This is an integral membrane protein located
specifically in mitochondria of eukaryotes to perform electron transport for the synthesis of
energy in the form of ATP.
Coenzyme Q – cytochrome c oxidoreductase (EC 1.10.2.2) is present in mitochondria. This
enzyme is essential for.
The respiratory chain is made up of five enzyme complexes embedded in the inner mitochondrial membrane as well as mobile electron carriers. Electrons are transferred sequentially from donors like NADH to a series of carriers - flavoproteins, iron-sulfur proteins, coenzyme Q, and cytochromes. This ultimately results in electrons combining with oxygen to produce water. The process establishes a proton gradient used by ATP synthase to generate ATP, the cell's energy currency.
Similar to Electron Transport Chain lecture.ppt (20)
Co-Chairs, Val J. Lowe, MD, and Cyrus A. Raji, MD, PhD, prepared useful Practice Aids pertaining to Alzheimer’s disease for this CME/AAPA activity titled “Alzheimer’s Disease Case Conference: Gearing Up for the Expanding Role of Neuroradiology in Diagnosis and Treatment.” For the full presentation, downloadable Practice Aids, and complete CME/AAPA information, and to apply for credit, please visit us at https://bit.ly/3PvVY25. CME/AAPA credit will be available until June 28, 2025.
Are you looking for a long-lasting solution to your missing tooth?
Dental implants are the most common type of method for replacing the missing tooth. Unlike dentures or bridges, implants are surgically placed in the jawbone. In layman’s terms, a dental implant is similar to the natural root of the tooth. It offers a stable foundation for the artificial tooth giving it the look, feel, and function similar to the natural tooth.
DECLARATION OF HELSINKI - History and principlesanaghabharat01
This SlideShare presentation provides a comprehensive overview of the Declaration of Helsinki, a foundational document outlining ethical guidelines for conducting medical research involving human subjects.
5-hydroxytryptamine or 5-HT or Serotonin is a neurotransmitter that serves a range of roles in the human body. It is sometimes referred to as the happy chemical since it promotes overall well-being and happiness.
It is mostly found in the brain, intestines, and blood platelets.
5-HT is utilised to transport messages between nerve cells, is known to be involved in smooth muscle contraction, and adds to overall well-being and pleasure, among other benefits. 5-HT regulates the body's sleep-wake cycles and internal clock by acting as a precursor to melatonin.
It is hypothesised to regulate hunger, emotions, motor, cognitive, and autonomic processes.
Lecture 6 -- Memory 2015.pptlearning occurs when a stimulus (unconditioned st...AyushGadhvi1
learning occurs when a stimulus (unconditioned stimulus) eliciting a response (unconditioned response) • is paired with another stimulus (conditioned stimulus)
How to Control Your Asthma Tips by gokuldas hospital.Gokuldas Hospital
Respiratory issues like asthma are the most sensitive issue that is affecting millions worldwide. It hampers the daily activities leaving the body tired and breathless.
The key to a good grip on asthma is proper knowledge and management strategies. Understanding the patient-specific symptoms and carving out an effective treatment likewise is the best way to keep asthma under control.
low birth weight presentation. Low birth weight (LBW) infant is defined as the one whose birth weight is less than 2500g irrespective of their gestational age. Premature birth and low birth weight(LBW) is still a serious problem in newborn. Causing high morbidity and mortality rate worldwide. The nursing care provide to low birth weight babies is crucial in promoting their overall health and development. Through careful assessment, diagnosis,, planning, and evaluation plays a vital role in ensuring these vulnerable infants receive the specialize care they need. In India every third of the infant weight less than 2500g.
Birth period, socioeconomical status, nutritional and intrauterine environment are the factors influencing low birth weight
2. Oxidative phosphorylation
Mitochondria, has two menbranes:
The outer mitochondrial membrane is
readily permeable to small molecules (Mr
5,000) and ions, which move freely
through transmembrane channels formed by
a family of integral membrane proteins
called porins.
The inner membrane is impermeable to
most small molecules and ions, including
protons (H).
the only species that cross this membrane
do so through specific transporters.
The selectively permeable inner
membrane segregates the intermediates and
enzymes of cytosolic metabolic pathways
from those of metabolic processes occurring
in the matrix.
3. Electron Carriers
FMN (Flavin MonoNucleotide) is a prosthetic group of
some flavoproteins.
It is similar in structure to FAD (Flavin Adenine
Dinucleotide), but lacking the adenine nucleotide.
FMN (like FAD) can accept 2 e- + 2 H+ to form FMNH2.
Oxidative phosphorylation begins with the entry of
electrons into the respiratory chain.
Dehydrogenases collect electrons from catabolic pathways
and funnel them into universal electron acceptors—
nicotinamide nucleotides (NAD or NADP) or flavin
nucleotides (FMN or FAD).
4. FMN, when bound at the active site of some enzymes, can
accept 1 e- to form the half-reduced semiquinone radical.
The semiquinone can accept a 2nd e- to yield FMNH2.
Since it can accept/donate 1 or 2 e-, FMN has an important
role mediating e- transfer between carriers that transfer 2e-
(e.g., NADH) & those that can accept only 1e- (e.g., Fe+++).
C
C
C
H
C
C
H
C
N
C
C
N
N
C
NH
C
H3C
H3C
O
O
CH2
HC
HC
HC
H2C
OH
O P O-
O
O-
OH
OH
C
C
C
H
C
C
H
C
N
C
C
H
N
N
C
NH
C
H3C
H3C
O
O
CH2
HC
HC
HC
H2C
OH
O P O-
O
O-
OH
OH
C
C
C
H
C
C
H
C
N
C
C
H
N
N
H
C
NH
C
H3C
H3C
O
O
CH2
HC
HC
HC
H2C
OH
O P O-
O
O-
OH
OH
e-
+ H+
e-
+ H+
FMN FMNH2
FMNH·
6. NAD(P)H
Nicotinamide nucleotide–linked dehydrogenases catalyze
reversible reactions of the following general types:
Neither NADH nor NADPH can cross the inner mitochondrial
membrane, but the electrons they carry can be shuttled across
indirectly.
How?
9. In addition to NAD and flavoproteins, three other types of electron-
carrying molecules function in the respiratory
chain:
Ubiquinone (Coenzyme Q).
Cytochromes
Iron sulfur proteins
10. Is the only non-protein component of electron transport chain.
Coenzyme Q (CoQ, Q, ubiquinone) is very hydrophobic.
It dissolves in the hydrocarbon core of the inner mitochondrial
membrane.
It includes a long isoprenoid tail, with multiple units having a
carbon skeleton comparable to that of isoprene.
In human cells, most often n = 10.
O
O
CH3O
CH3
CH3O
(CH2 CH C CH2)nH
CH3
coenzyme Q
isoprene
H2C C C CH2
CH3
H
Coenzyme Q (Ubiquinone ,CoQ, Q)
11. Ubiquinone can accept one
electron to become the
semiquinone radical (∙QH) or
two electrons to form ubiquinol
(QH2) :
Coenzyme Q functions as a
mobile e- carrier within the
mitochondrial inner membrane.
12. The Heme prosthetic group of
cytochromescontains an iron atom in a
porphyrin ring system.
The Fe is bonded to 4 N atoms of the
porphyrin ring.
The iron participates in redox reactions
and oscillates between Fe2+ and Fe3+ states.
Hemes in the 3 classes of cytochrome
(a, b, c) differ slightly in substituents on
the porphyrin ring system
Cytochromes
The cytochromes are proteins with characteristic strong
absorption of visible light, due to their iron containing heme
prosthetic groups.
Three types exists: Cytochrome a,b and c.
Are distinguished by differences in their light-absorption spectra.
13. Prosthetic groups of cytochromes
Heme is a prosthetic group of cytochromes
Mitochondria has 3 classes of cytochromes,designated a, b,
and c
Found in Hb
The heme iron atom can
undergo a 1 electron
transition between ferric and
ferrous states:
Fe3+ + e- <--> Fe2+
14. Only heme c is covalently linked to the protein via thioether
bonds to cysteine residues.
15. Heme a is unique in having a long farnesyl side-chain
that includes 3 isoprenoid units.
Note: A common feature is 2 propionate side-chains.
16. Cytochromes are proteins with heme prosthetic groups.
They absorb light at characteristic wavelengths.
Absorbance changes upon oxidation/reduction of the
heme iron provide a basis for monitoring heme redox state.
Some cytochromes are part of large integral membrane
complexes, each consisting of several polypeptides &
including multiple electron carriers.
E.g., hemes a & a3 that are part of the respiratory chain
complex IV are often referred to as cytochromes a & a3.
Cytochrome c is instead a small, water-soluble protein
with a single heme group.
17. Iron-sulfur centers (Fe-S) are prosthetic groups containing
2,3,4 or 8 iron atoms complexed to elemental & cysteine S
Cysteine residues provide S ligands to the iron, while also
holding these prosthetic groups in place within the protein.
Iron-sulfur centers
18. E.g., a 4-Fe center might cycle between redox states:
Fe+++
3, Fe++
1 (oxidized) + 1 e- Fe+++
2, Fe++
2 (reduced)
Fe
Fe
S
S
S
Fe
Fe
S
S
S
S
S
Cys
Cys
Cys
Cys
S
Fe
S
Fe
S
S
S
S
Cys
Cys
Cys
Cys
Iron-Sulfur Centers
Electron transfer proteins may
contain multiple Fe-S centers.
Iron-sulfur centers transfer
only one electron, even if they
contain two or more iron
atoms, because of the close
proximity of the iron atoms.
19. Most constitutents of the respiratory chain are
embedded in the inner mitochondrial membrane (or in
the cytoplasmic membrane of aerobic bacteria).
The inner mitochondrial membrane has infoldings
called cristae that increase the membrane area.
matrix
inner
membrane
outer
membrane
inter-
membrane
space
mitochondrion
cristae
Respiratory
Chain:
20. Within each complex, electrons pass sequentially through
a series of electron carriers.
CoQ is located in the lipid core of the membrane. There
are also binding sites for CoQ within protein complexes
with which it interacts.
Cytochrome c resides in the intermembrane space.
It alternately binds to complex III or IV during e- transfer.
Electrons are
transferred from
NADH O2 via
multisubunit
inner membrane
complexes I,II
III & IV, plus
CoQ & cyt c.
21. There is also evidence for
the existence of stable
supramolecular
aggregates containing
multiple complexes.
Individual respiratory chain
complexes have been isolated and
their composition determined.
Components of the electron
transport chain can be purified
from the mitochondrial inner
membrane
22. Method for determining the sequence if electron carreirs
Inhibitors at various points of the respiratory chain were used
23. Composition of Respiratory Chain Complexes
Complex Name
No. of
Proteins
Prosthetic
Groups
Complex I NADH
Dehydrogenase
46 FMN,
9 Fe-S cntrs.
Complex II Succinate-CoQ
Reductase
5 FAD, cyt b560,
3 Fe-S cntrs.
Complex III CoQ-cyt c
Reductase
11 cyt bH, cyt bL,
cyt c1, Fe-SRieske
Complex IV Cytochrome
Oxidase
13 cyt a, cyt a3,
CuA, CuB
24. NADH + H+ + Q NAD+ + QH2
An atomic-level structure is not yet available for the entire
complex I, which in mammals includes at least 46 proteins,
along with prosthetic groups FMN & several Fe-S centers.
Complex I
catalyzes
oxidation of
NADH, with
reduction of
coenzyme Q:
25. The peripheral domain, containing the FMN that accepts
2e- from NADH, protrudes into the mitochondrial matrix.
Iron-sulfur centers are also located in the hydrophilic
peripheral domain, where they form a pathway for e-
transfer from FMN to coenzyme Q.
A binding site for coenzyme Q is thought be close to the
interface between peripheral and intra-membrane domains.
Complex I is
L-shaped.
26. o
o
r
r
o
o
r
Mechanism of e- transfer in Complex I
Estimated mass of this complex 850 kD
Involves more than 30 polypeptide chains
One molecule of FMN
As many as 7 Fe-S clusters (2Fe-2S & 4Fe-4S)
Precise mechanism of this complex is unknown
27. The initial electron transfers are:
NADH + H+ + FMN NAD+ + FMNH2
FMNH2 + (Fe-S)ox FMNH· + (Fe-S)red + H+
After Fe-S is reoxidized by transfer of the electron to
the next iron-sulfur center in the pathway:
FMNH· + (Fe-S)ox FMN + (Fe-S)red + H+
Electrons pass through a series of iron-sulfur centers,
and are eventually transferred to coenzyme Q.
Coenzyme Q accepts 2e- and picks up 2H+ to yield
the fully reduced QH2.
28. Inhibitors of complex 1
Amytal (a barbiturate drug), rotenone (a plant product commonly
used as an insecticide), and piericidin A (anantibiotic) inhibit
electron flow from the Fe-S centers of Complex I to ubiquinone and
therefore block the overall process of oxidative phosphorylation.
29. FAD is reduced to FADH2 during oxidation of succinate
to fumarate.
FADH2 is then reoxidized by transfer of electrons through
a series of 3 iron-sulfur centers to CoQ, yielding QH2.
The QH2 product is then reoxidized via complex III,
providing a pathway for transfer of electrons from
succinate into the respiratory chain.
COO-
C
C
COO-
H H
H H
COO-
C
C
COO-
H
H
Q QH2
via FAD
succinate fumarate
Succinate Dehydrogenase
(Complex II)
Succinate Dehydrogenase
of the Krebs Cycle is also
called complex II or
Succinate-CoQ Reductase.
FAD is the initial e-
acceptor.
Complex II
30. H+ transport
does not occur
in this complex
Complex II
Succinate-CoQ Reductase
or
Succinate dehydrogenase
(from TCA cycle!)
Mass of 100 – 140 kD
Composed of 4 subunits, including 2 Fe-S proteins
Three types of Fe-S cluster: 4Fe-4S, 3Fe-4S, 2Fe-2S
Path: Succinate FADH2 2Fe2+ UQH2
31. Path of electrons from NADH, succinate, fatty
acyl–CoA, and glycerol 3-phosphate to ubiquinone.
33. Complex III (Cytochrome Reductase)
Accepts electrons from coenzyme QH2 that is
generated by electron transfer in complexes I & II.
Couples the transfer of electrons from ubiquinol (QH2)
to cytochrome c with the vectorial transport of protons
from the matrix to the intermembrane space.
Cytochrome c1, a prosthetic group within complex III,
reduces cytochrome c, which is the electron donor to
complex IV.
35. • Antimycin A:
An antibiotic blocks electron transport by
inhibiting cytochrome reductase.
• BAL (British anti lewisite):
Used as therapeutic agent in the cases of
arsenic poisoning. It inhibits activity of
cytochrome reductase.
Inhibitors of complex III
36. Cytochrome oxidase (complex IV) carries out the
following irreversible reaction:
The four electrons are transferred into the complex one
at a time from cytochrome c.
37. • Cyanide (CN)
A powerful poison that inhibit cytochrome oxidase by
combining with cytochrome a3.
Cyanide may arise from cyanogenic substance.
• Carbon monoxide (CO)
It inhibits activity of cytochrome oxidase. (a pollutant).
• 3. Hydrogen sulfide (H2S)
It inhibits cytochrome oxidase. H2S toxicity occurs during
oil drilling operations.
It is toxic as cyanide. It is a part of natural gas.
• Azide:
Sodium azide also inhibits cytochrome oxidase activity.
Inhibitors of complex IV
38. Proton gradient
The Energy of Electron Transfer Is Efficiently Conserved in a
Proton Gradient
• Proton gradient created as electrons
transferred to oxygen forming water
10 H+ / NADH
6 H+ / FADH2
40. F1F0-ATP synthase of E.Coli.
F1 portion
is composed of several subunits.
It contains three α, three β and one γ, δ and ε sub
units,designated as α3 β3 γ1 δ1 ε1.
F0 portion
is composed of one a, two b, and twelve c subunits.
Binding-change model for ATP synthase.
Proposed by Paul Boyer.
The F1 complex has three nonequivalent adenine
nucleotide–binding sites, one for each pair of α and β
subunits.
At any given moment, one of these sites is in the β-ATP
conformation (which binds ATP tightly), a second
is in the β-ADP (loose-binding) conformation, and a third is
in the β-empty (very-loose-binding) conformation.
proton-motive force causes rotation of the central shaft—
the γ subunit comes into contact with each αβ subunit pair in
Succession, producing cooperative conformational changes.
41. • Proton dependant ATP synthetase
– Uses proton gradient to make ATP
– Protons pumped through channel on enzyme
• From intermembrane space into matrix
• ~4 H+ / ATP
– Called chemiosmotic coupling theory.
Other theories include: Chemical coupling theory &
Conformational coupling theory.
Generation of ATP
NADH
10 H+ X 1 ATP = 2.5 ATP
4 H+
FADH2
6 H+ X 1 ATP = 1.5 ATP
4 H+
Totals
42. Uncouplers of Oxidative phosphorylation
These compounds dissociates or uncouples oxidation in
respiratory chain from phosphorylation.
So, the oxidation takes place without ATP synthesis.
Examples:
• 2, 4-dinitrophenol
• Dinitrocresol
• Salicylanilides
• Pentachlorophenol
• CCCP (Carbonylcyanide chloromethoxy phenyl hydrazone).
• FCCP (Carbanoyl cyanide p. trifluoromethoxy phenyl
hydrazone).
Thermogenin
43. Regulation of Oxidative
phosphorylation.
Oxidative phosphorylation in the
respiratory chain is subjected to
regulation like any metabolic pathway.
The rate of respiration is generally
limited by the availability of substrates
such as: ADP, Pi, NADH, FADH2 and
O2.
44.
45. Oxidative phosphorylation
• This is the process by which ADP is phosphorylated
with inorganic phosphate to generate ATP.
• NADH2 has a central role in this process.
• Electrons are transferred down the respiratory chain
from NADH2 to oxygen. This is because NADH2 is a
strong electron donor while oxygen is a strong
electron acceptor.