A
Report on
Enzymes
By
Sanjay Jagarwal
(10112047)
Chemical B.tech 3rd year
Enzyme Action
Enzymes: proteins that function as biological catalysts.
Catalyst: a substance that speeds up a chemical rea...
“Lock and key” model
However certain substances can bind to the enzyme at sites other than the
Active site and modify its ...
Induced Fit
This model proposes that the initial interaction between enzyme
and substrate is relatively weak, but that the...
Enzyme reactions
enzyme + productenzyme-substrate complex
E +PES
enzyme + substrate enzyme-substrate complex
E +S ES
Mechanisms
Enzymes can act in several ways, all of which lower ΔG‡
(Gibbs energy):
• Lowering the activation energy by cre...
Enzyme activity
Four Variables
Temperature
pH
Enzyme Concentration
Substrate Concentration
RateofReaction
Temperature
RateofReaction
Temperature
0 20 30 5010 40 60
RateofReaction
Temperature
0 20 30 5010 40 60
40oC - denatures
5- 40oC
Increase in Activity
<5oC - inactive
Effect of heat on enzyme activty
If you heat the protein above its optimal temperature
bonds break
meaning the protein los...
Effect of heat on enzyme activty
Denaturing the protein
Effect of heat on enzyme activty
Denaturing the protein
ACTIVE SITE CHANGES SHAPE
SO SUBSTRATE NO LONGER FITS
Even if temp...
pH effect:
• The ph scale measures how acidic or alkaline a
substance is.
• The chemical properties of many solutions enab...
pH scale
RateofReaction
pH
RateofReaction
pH
1 3 42 5 6 7 8 9
RateofReaction
pH
1 3 42 5 6 7 8 9
Narrow pH optima
RateofReaction
pH
1 3 42 5 6 7 8 9
Narrow pH optima
WHY?
RateofReaction
pH
1 3 42 5 6 7 8 9
Narrow pH optima
Disrupt Ionic bonds - Structure
Effect charged residues at active
site
RateofReaction
Enzyme Concentration
RateofReaction
Enzyme Concentration
Enzyme Concentration
RateofReaction
Substrate Concentration
RateofReaction
Substrate Concentration
Substrate Concentration
RateofReaction
Substrate Concentration
Substrate Concentration
Active sites full- maximum turnover
METABOLISM
• Metabolism is the sum of all biochemical
reactions occurring in living cells.
• These reactions can be divide...
• Involves the synthesis
of complex molecules
from simpler molecules
which requires energy
input.
• Involves the breakdown...
• Energy releasing processes, ones that
"generate" energy, are termed exergonic
reactions.
• Reactions that require energy...
• This kind of reaction is not termed a
spontaneous reaction. In order to go from
the initial state to the final state a
c...
• The speed V means the number of reactions per
second that are catalyzed by an enzyme.
• With increasing substrate concen...
Vo = Vmax
KM
• Vo = Initial reaction velocity
• Vmax = Maximum velocity
• Km = Michaelis constant
• [S] = Substrate concen...
Enzyme Nomenclature
Functional classification:
It is widely used. It takes into account the name of the
substrate of the e...
When the enzyme uses two substrates and are described
by specifying both
radicals of the donor substrate
the acceptor subs...
Enzyme Nomenclature official
1: oxidoreductases, which catalyze electron transfer
2: The transferases, which catalyze the ...
The different types of enzymes:
• 4.1 - of redox enzymes and oxygen fixation
• 4.1.1 - dehydrogenation of the alcohol,
car...
• A non protein component of enzymes is called the
cofactor.
• If the cofactor is organic, then it is called a coenzyme.
•...
• In the graphic on the left is the structure for the
coenzyme, NAD+, Nicotinamide Adenine
Dinucleotide.
• Nicotinamide is...
Vitamin Coenzyme Function
niacin
nicotinamide adenine
dinucleotide (NAD+)
oxidation or
hydrogen transfer
riboflavin
flavin...
• Coenzyme Q10 is a fat-soluble nutrient also known as
CoQ10, vitamin Q10, ubidecarenone, or ubiquinone.
• It is a natural...
• Quinones are substances found in all plants
and animals.
• The variety found in humans has a 10-unit
side chain in its m...
• Enzyme inhibitors are molecules that interact in
some way with the enzyme to prevent it from
working in the normal manne...
• A nonspecific inhibition effects all enzymes in
the same way.
• Non-specific methods of inhibition include any
physical ...
• Temperature: Usually, the reaction rate increases
with temperature, but with enzyme reactions, a
point is reached when t...
• A competitive inhibitor is any compound
which closely resembles the chemical
structure and molecular geometry of the
sub...
• The inhibitor is "stuck" on the enzyme and prevents
any substrate molecules from reacting with the
enzyme.
• However, a ...
• A noncompetitive inhibitor is a substance that forms
strong covalent bonds with an enzyme and
consequently may not be di...
Noncompetitive Inhibitor Action:
• If the inhibition is at a place remote from the
active site, this is called allosteric inhibition.
• Allosteric means "o...
• There are approximately 3000 enzymes which
have been characterised.
• These are grouped into six main classes
according ...
1.Oxidoreductases
• These enzymes catalyse oxidation and
reduction reactions involving the transfer of
hydrogen atoms or e...
– catalyse hydrogen transfer from the substrate to
molecular oxygen producing hydrogen peroxide as
a by-product. An exampl...
Dehydrogenases
– catalyse hydrogen transfer from the substrate to a
nicotinamide adenine dinucleotide cofactor
(NAD+). An ...
Peroxidases
– catalyse oxidation of a substrate by hydrogen
peroxide.
– An example of this type of enzyme is horseradish
p...
– catalyse substrate oxidation by molecular oxygen.
– The reduced product of the reaction in this case is
water and not hy...
2.Transferases
• These enzymes transfer C, N, P or S containing
groups (alkyl, acyl, aldehyde, amino,
phosphate or glucosy...
3.Hydrolases
• These enzymes catalyse cleavage reactions or
the reverse fragment condensations.
• According to the type of...
4.Lyases
• These enzymes non-hydrolytically remove
groups from their substrates with the
concomitant formation of double b...
5.Isomerases
• These enzymes catalyse intramolecular
rearrangements and are subdivided into;
» racemases
» epimerases
» mu...
6.Ligases
• Ligases split C-C, C-O, C-N, C-S and C-halogen bonds
without hydrolysis or oxidation.
• The reaction is usuall...
The End
Enzymes
Enzymes
Enzymes
Enzymes
Enzymes
Enzymes
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Enzymes

  1. 1. A Report on Enzymes By Sanjay Jagarwal (10112047) Chemical B.tech 3rd year
  2. 2. Enzyme Action Enzymes: proteins that function as biological catalysts. Catalyst: a substance that speeds up a chemical reaction and is not changed by the reaction. Specificity:Enzymes are usually very specific as to Which reaction they catalyze. Highly specific Enzymes follows "proof-reading" mechanisms
  3. 3. “Lock and key” model However certain substances can bind to the enzyme at sites other than the Active site and modify its activity (inhibitors/co-factors) Idea that the enzyme is flexible.
  4. 4. Induced Fit This model proposes that the initial interaction between enzyme and substrate is relatively weak, but that these weak interactions rapidly induce conformational changes in the enzyme that strengthen binding.
  5. 5. Enzyme reactions enzyme + productenzyme-substrate complex E +PES enzyme + substrate enzyme-substrate complex E +S ES
  6. 6. Mechanisms Enzymes can act in several ways, all of which lower ΔG‡ (Gibbs energy): • Lowering the activation energy by creating an environment in which the transition state is stabilized • Lowering the energy of the transition state, but without distorting the substrate. • Providing an alternative pathway. • Reducing the reaction entropy change by bringing substrates together in the correct orientation to react.
  7. 7. Enzyme activity Four Variables Temperature pH Enzyme Concentration Substrate Concentration
  8. 8. RateofReaction Temperature
  9. 9. RateofReaction Temperature 0 20 30 5010 40 60
  10. 10. RateofReaction Temperature 0 20 30 5010 40 60 40oC - denatures 5- 40oC Increase in Activity <5oC - inactive
  11. 11. Effect of heat on enzyme activty If you heat the protein above its optimal temperature bonds break meaning the protein loses it secondary and tertiary structure
  12. 12. Effect of heat on enzyme activty Denaturing the protein
  13. 13. Effect of heat on enzyme activty Denaturing the protein ACTIVE SITE CHANGES SHAPE SO SUBSTRATE NO LONGER FITS Even if temperature lowered – enzyme can’t regain its correct shape
  14. 14. pH effect: • The ph scale measures how acidic or alkaline a substance is. • The chemical properties of many solutions enable them to be divided into 3 categories: 1) Neutral: solutions with a ph of 7. 2) Alkaline: solutions with a ph greater than 7 3) Acidic: solutions with a ph less than 7.
  15. 15. pH scale
  16. 16. RateofReaction pH
  17. 17. RateofReaction pH 1 3 42 5 6 7 8 9
  18. 18. RateofReaction pH 1 3 42 5 6 7 8 9 Narrow pH optima
  19. 19. RateofReaction pH 1 3 42 5 6 7 8 9 Narrow pH optima WHY?
  20. 20. RateofReaction pH 1 3 42 5 6 7 8 9 Narrow pH optima Disrupt Ionic bonds - Structure Effect charged residues at active site
  21. 21. RateofReaction Enzyme Concentration
  22. 22. RateofReaction Enzyme Concentration Enzyme Concentration
  23. 23. RateofReaction Substrate Concentration
  24. 24. RateofReaction Substrate Concentration Substrate Concentration
  25. 25. RateofReaction Substrate Concentration Substrate Concentration Active sites full- maximum turnover
  26. 26. METABOLISM • Metabolism is the sum of all biochemical reactions occurring in living cells. • These reactions can be divided into two main groups: – 1) ANABOLISM – 2) CATABOLISM
  27. 27. • Involves the synthesis of complex molecules from simpler molecules which requires energy input. • Involves the breakdown of complex molecules into simpler molecules involving hydrolysis or oxidation and the release of energy.
  28. 28. • Energy releasing processes, ones that "generate" energy, are termed exergonic reactions. • Reactions that require energy to initiate the reaction are known as endergonic reactions. • All natural processes tend to proceed in such a direction that the disorder or randomness of the universe increases Exergonic Reaction
  29. 29. • This kind of reaction is not termed a spontaneous reaction. In order to go from the initial state to the final state a considerable amount of energy must be imparted to the system. • These kinds of reactions are associated with a positive number (+G). Endergonic Reaction
  30. 30. • The speed V means the number of reactions per second that are catalyzed by an enzyme. • With increasing substrate concentration [S], the enzyme is asymptotically approaching its maximum speed Vmax, but never actually reaching it. • Because of that, no [S] for Vmax can be given. • Instead, the characteristic value for the enzyme is defined by the substrate concentration at its half- maximum speed (Vmax/2). • This KM value is also called Michaelis-Menten constant.
  31. 31. Vo = Vmax KM • Vo = Initial reaction velocity • Vmax = Maximum velocity • Km = Michaelis constant • [S] = Substrate concentration
  32. 32. Enzyme Nomenclature Functional classification: It is widely used. It takes into account the name of the substrate of the enzyme and the type of catalyzed reaction. To designate an enzyme is indicated: the name of the first substrate then the type of reaction catalyzed Finally we add the suffix ase. For example: - Glucose-6-phosphate isomerase - Isocitrate lyase - Pyruvate carboxylase
  33. 33. When the enzyme uses two substrates and are described by specifying both radicals of the donor substrate the acceptor substrate and then released the radical exchanged the radical the type of reaction finally added ase for example - ATP-glucose phosphotransferase - UDPglucose-fructose glucosyltransferase - Glutamate pyruvate transaminase
  34. 34. Enzyme Nomenclature official 1: oxidoreductases, which catalyze electron transfer 2: The transferases, which catalyze the transfer of groups 3: hydrolases which catalyze hydrolysis reactions 4: lyases, which catalyze the addition of groups to double bonds or vice versa 5: isomerases which catalyze the transfer of groups in one molecule to produce isomeric forms (the conversion of an amino acid D-amino acid in L 'for example) 6: ligases, which form links CC, CS, CN and CO during condensation reactions coupled with the use of ATP.
  35. 35. The different types of enzymes: • 4.1 - of redox enzymes and oxygen fixation • 4.1.1 - dehydrogenation of the alcohol, carbonyl or • carboxyl • 4.1.2 - dehydrogenases appear by double bonds • 4.1.3 - dehydrogenases acting on functions nitrogenous • 4.1.4 - enzymes involved in the transfer of electrons in the mitochondria • 4.1.5 - oxygenases • 4.2 - transferases • 4.2.1 - enzymes transferring a methyl group • 4.2.2 - the transferring enzymes radicals has more carbons • 4.2.3 - the transferring enzymes of carbohydrate molecules • 4.2.4 - aminotransferases • 4.2.5 - Phosphotransferases • 4.3 - hydrolases • 4.3.1 - carbohydrate hydrolases • 4.3.2 - hydrolases phosphoric esters of monosaccharides 4.3.3 lipid hydrolases 4.3.4 - hydrolases of peptides and proteins 4.3.5 - hydrolases nucleosides, nucleotides and nucleic acids 4.3.6 - hydrolase esters or phosphoric anhydride 4.4 - lyases and synthases 4.4.1 - decarboxylases 4.4.2 - aldehyde-lyases 4.4.3 - acyl-lyase or acylsynthase 4.4.4 - hydratases and dehydratases 4.5 - isomerases 4.5.1 - epimerization 4.5.2 - intramolecular redox 4.5.3 - transport of radicals 4.6 - ligases (synthetases) 4.6.1 - forming links ligases c-o 4.6.2 - bond forming ligase c-c 4.6.3 - links ligases c-s 4.6.4 - links ligases c-n
  36. 36. • A non protein component of enzymes is called the cofactor. • If the cofactor is organic, then it is called a coenzyme. • Coenzymes are relatively small molecules compared to the protein part of the enzyme. • Many of the coenzymes are derived from vitamins. • The coenzymes make up a part of the active site, since without the coenzyme, the enzyme will not function. Enzyme Cofactor
  37. 37. • In the graphic on the left is the structure for the coenzyme, NAD+, Nicotinamide Adenine Dinucleotide. • Nicotinamide is from the niacin vitamin. • The NAD+ coenzyme is involved with many types of oxidation reactions where alcohols are converted to ketones or aldehydes. Enzyme Cofactor
  38. 38. Vitamin Coenzyme Function niacin nicotinamide adenine dinucleotide (NAD+) oxidation or hydrogen transfer riboflavin flavin adenine dinucleotide (FAD) oxidation or hydrogen transfer pantothenic acid coenzyme A (CoA) Acetyl group carrier vitamin B-12 coenzyme B-12 Methyl group transfer thiamin (B-1) thiaminpyrophosphate (TPP) Aldehyde group transfer
  39. 39. • Coenzyme Q10 is a fat-soluble nutrient also known as CoQ10, vitamin Q10, ubidecarenone, or ubiquinone. • It is a natural product of the human body that is primarily found in the mitochondria, which are the cellular organelles that produce energy. • It occurs in most tissues of the human body; however, the highest concentrations are found in the heart, liver, kidneys, and pancreas. • Ubiquinone takes its name from a combination of the word ubiquitous, meaning something that is found everywhere, and quinone 10. Co-enzymes
  40. 40. • Quinones are substances found in all plants and animals. • The variety found in humans has a 10-unit side chain in its molecular structure. • Apart from the important process that provides energy, CoQ10 also stabilizes cell membranes and acts as an antioxidant. • In this capacity, it destroys free radicals, which are unstable molecules that can damage normal cells.
  41. 41. • Enzyme inhibitors are molecules that interact in some way with the enzyme to prevent it from working in the normal manner. • There are a variety of types of inhibitors including: nonspecific, irreversible, reversible - competitive and noncompetitive. • Poisons and drugs are examples of enzyme inhibitors. Enzyme inhibitors
  42. 42. • A nonspecific inhibition effects all enzymes in the same way. • Non-specific methods of inhibition include any physical or chemical changes which ultimately denatures the protein portion of the enzyme and are therefore irreversible. Non Specific Inhibitor
  43. 43. • Temperature: Usually, the reaction rate increases with temperature, but with enzyme reactions, a point is reached when the reaction rate decreases with increasing temperature. • At high temperatures the protein part of the enzyme begins to denature, thus inhibiting the reaction. Example:
  44. 44. • A competitive inhibitor is any compound which closely resembles the chemical structure and molecular geometry of the substrate. • The inhibitor competes for the same active site as the substrate molecule. • The inhibitor may interact with the enzyme at the active site, but no reaction takes place. Competitive Inhibitor
  45. 45. • The inhibitor is "stuck" on the enzyme and prevents any substrate molecules from reacting with the enzyme. • However, a competitive inhibition is usually reversible if sufficient substrate molecules are available to ultimately displace the inhibitor. • Therefore, the amount of enzyme inhibition depends upon the inhibitor concentration, substrate concentration, and the relative affinities of the inhibitor and substrate for the active site. Competitive Inhibitor
  46. 46. • A noncompetitive inhibitor is a substance that forms strong covalent bonds with an enzyme and consequently may not be displaced by the addition of excess substrate. • Therefore, noncompetitive inhibition is irreversible. • A noncompetitive inhibitor may be bonded at, near, or remote from the active site. In any case, the basic structure of the enzyme is modified to the degree that it ceases to work. Non-Competitive Inhibitor
  47. 47. Noncompetitive Inhibitor Action:
  48. 48. • If the inhibition is at a place remote from the active site, this is called allosteric inhibition. • Allosteric means "other site" or "other structure". • The interaction of an inhibitor at an allosteric site changes the structure of the enzyme so that the active site is also changed. Non-Competitive Inhibitor
  49. 49. • There are approximately 3000 enzymes which have been characterised. • These are grouped into six main classes according to the type of reaction catalysed. • At present, only a limited number are used in enzyme electrodes or for other analytical purposes.
  50. 50. 1.Oxidoreductases • These enzymes catalyse oxidation and reduction reactions involving the transfer of hydrogen atoms or electrons. • The following are of particular importance in the design of enzyme electrodes. • This group can be further divided into 4 main classes.
  51. 51. – catalyse hydrogen transfer from the substrate to molecular oxygen producing hydrogen peroxide as a by-product. An example of this is FAD dependent glucose oxidase which catalyses the following reaction: – b-D-glucose + O2 = gluconolactone + H2O2 Oxidases
  52. 52. Dehydrogenases – catalyse hydrogen transfer from the substrate to a nicotinamide adenine dinucleotide cofactor (NAD+). An example of this is lactate dehydrogenase which catalyses the following reaction: – Lactate + NAD+ = Pyruvate + NADH + H+
  53. 53. Peroxidases – catalyse oxidation of a substrate by hydrogen peroxide. – An example of this type of enzyme is horseradish peroxidase which catalyses the oxidation of a number of different reducing substances (dyes, amines, hydroquinones etc.) and the concomitant reduction of hydrogen peroxide. – The reaction below illustrates the oxidation of neutral ferrocene to ferricinium in the presence of hydrogen peroxide: – 2[Fe(Cp)2] + H2O2 + 2H+= 2[Fe(Cp)2]+ + 2 H2O
  54. 54. – catalyse substrate oxidation by molecular oxygen. – The reduced product of the reaction in this case is water and not hydrogen peroxide. – An example of this is the oxidation of lactate to acetate catalysed by lactate-2-monooxygenase. – lactate + O2 = acetate + CO2 + H2O Oxygenases
  55. 55. 2.Transferases • These enzymes transfer C, N, P or S containing groups (alkyl, acyl, aldehyde, amino, phosphate or glucosyl) from one substrate to another. • Transaminases, transketolases, transaldolases and transmethylases belong to this group.
  56. 56. 3.Hydrolases • These enzymes catalyse cleavage reactions or the reverse fragment condensations. • According to the type of bond cleaved, a distinction is made between peptidases, esterases, lipases, glycosidases, phosphatases and so on. • Examples of this class of enzyme include; cholesterol esterase, alkaline phosphatase and glucoamylase.
  57. 57. 4.Lyases • These enzymes non-hydrolytically remove groups from their substrates with the concomitant formation of double bonds or alternatively add new groups across double bonds.
  58. 58. 5.Isomerases • These enzymes catalyse intramolecular rearrangements and are subdivided into; » racemases » epimerases » mutases » cis-trans-isomerases • An example of this class of enzyme is glucose isomerase which catalyses the isomerisation of glucose to fructose.
  59. 59. 6.Ligases • Ligases split C-C, C-O, C-N, C-S and C-halogen bonds without hydrolysis or oxidation. • The reaction is usually accompanied by the consumption of a high energy compound such as ATP and other nucleoside triphosphates. • An example of this type of enzyme is pyruvate carboxylase which catalyses the following reaction: • pyruvate + HCO3- + ATP = Oxaloacetate + ADP + Pi
  60. 60. The End

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