Principle of Biochemistry2-Amino Acids and Proteins     Course code: HFB324     Credit hours: 3 hours       Dr. Siham Grit...
Terms should be learned• Protein; molecule consisting of one or more  polypeptide chains• amino acid; an amino group and a...
• Enantiomers; two organic compounds that are  are mirror images; these compounds contain  one or more chiral carbons• L-a...
• R-group; (of an amino acid) one of twenty (or  more) different organic groups bonded to the  alpha carbon• Stereoisomers...
Composition and nature of proteins;• Proteins are complex organic compound found  in animal and plant tissues.• The protei...
Protein functions           1-Structural function• -Structural function   Component of all cell membranes• Component of cy...
Protein functions           2-Metabolic functions• 1-enzymatic function• Most specialized proteins with catalytic  activit...
• 2-hormones (Regulatory Proteins)• Help regulate cellular or physiological activity.• The cellular response to many hormo...
• G proteins are important signal transduction  molecules in cells• transmitting chemical signals originating from  outsid...
• 3-Immune function (Defense Proteins)• Defend organisms against invasion by other  species or protect them• Immunoglobuli...
• 4-Acid base balance buffering agent• Buffers ; are compounds that recover or (improve) a  change in pH that occur in res...
edema or swelling     Dr. Siham Gritly   12
• Protein molecules possess basic and acidic groups  (Amphoteric molecules )which act as H+  acceptors or donors respectiv...
• Protein buffer: COOH (acid) of amino acid  can lose H+ (COO-)• NH2 (amine) of amino acid can gain H+  (NH3+) (buffering ...
• 5-transport• Bind and carry molecules or ions to organs in  the blood plasma.• Lipoproteins in blood plasma carries lipi...
• 6-Energy sources• any amounts above the needed amino acids for  synthesis of tissues are metabolized and degraded.• *The...
7-Nutrient and Storage Proteins• Seeds of many plants store nutrient proteins  required for the growth of the germinating ...
Denaturation of proteins• Denaturation is the breakdown of all covalent  bonds causing change in shape and thus loss of  f...
Protein structure  Each protein has a unique shape or conformation. all proteinsare composed exclusively of subunits of am...
1-Primary structure of proteinsamino acids sequences• The primary structure of a protein simply  consists of its linear se...
2-Secondary structure• As peptide bonds are formed, aligning the  amino acids, hydrogen bonds form between  different amin...
2-Secondary structureThe α-helix coils of protein          Dr. Siham Gritly     22
Pleated Proteinthe polypeptide have portions that lie parallel to each other (held by hydrogenbonds) instead of in the alp...
3-Tertiary Structure of protein• the side chains (the R groups) of amino acids may fold  independently into a functional u...
Tertiary Structure of protein           Dr. Siham Gritly     25
• 5 kind of bonds stabilize tertiary structure• 1-van der Waals interaction (between  neighboring atoms) Van der Waals for...
• 3-hydrophobic interactions (between non  polar)• 4-ionic interactions (between oppositely  charged groups)• 5-disulphide...
Amino acid Cysteine                         disulphide linkages      composed of two cysteines linked by a disulfide bond ...
4-Quaternary Protein Structurethe structure formed by several protein molecules (polypeptide            chains), usually c...
4-Quaternary Protein Structure                                Haemoglobin structure             Dr. Siham Gritly          ...
Amino acidthe building block    of proteins     Dr. Siham Gritly   31
Amino Acid                  General structure of amino acid    The carbon atom next to the carboxyl group is called the α ...
Amino acids• Amino acids contain Carbon,  Hydrogen, Oxygen, Nitrogen, and sometimes Sulfur• Amino acids have two function ...
• The alpha carbon will have at its fourth  bonding site a side chain, or R group which  gives the amino acid its unique s...
• Some amino acids have R groups that are polar  (hydrophilic), interact with water at physiological pH  (O, N)• some R gr...
• Some with Amino Acids with Aliphatic R-  Groups nonpolar and hydrophobic  (Hydrophobicity increases with increasing  num...
• • Amino acids are joined together by a  dehydration synthesis of amino/carboxyl  groups forming a peptide bond.         ...
α-Amino Acids structure Found in ProteinsBackbone of the amino acids is red, R-groups are blackreference; Michael W King, ...
α-Amino Acids Found in Proteins              Backbone of the amino acids is red, R-groups are blackreference; Michael W Ki...
α-Amino Acids Found in ProteinsBackbone of the amino acids is red, R-groups are blackreference; Michael W King, PhD | ©996...
α-Amino Acids Found in Proteins              Backbone of the amino acids is red, R-groups are blackreference; Michael W Ki...
α-Amino Acids Found in Proteins              Backbone of the amino acids is red, R-groups are blackreference; Michael W Ki...
α-Amino Acids Found in Proteins                    Backbone of the amino acids is red, R-groups are black reference; Micha...
α-Amino Acids Found in Proteins                   Backbone of the amino acids is red, R-groups are blackreference; Michael...
The amino acids found in proteins have a common                 stereochemistry      Optical Properties of the Amino Acids...
• All of the amino acids in proteins exhibit the  same steric configuration as L-glyceraldehyde• the amino group is always...
Acid-Base Properties of the Amino                Acids• The α-COOH and α-NH2 groups in amino acids are  capable of ionizin...
the carboxyl group is stronger acid than the amino group. At   physiological pH (around 7.4) the carboxyl group will be   ...
• Carboxylic acid groups (−CO2H) can be  deprotonated to become negative  carboxylates (−CO2− ),• and α-amino groups (NH2−...
Amino acid and peptide linkage            Dr. Siham Gritly     50
Peptide linkageamino acids are the structural units of the body protein. They are all α amino-carboxylic acids. All amino ...
Peptide linkage  All peptides and polypeptides are polymers of α-                    amino acids• *A protein starts as a c...
• *The specific amino acids in the polypeptide  chain will determine its configuration, or  shape, and therefore, its func...
Essential and non essential amino acids             Essential                      NonessentialIsoleucine                 ...
Essential                       NonessentialValine                       Proline*                             Selenocystei...
• *Nonessential amino acids can be synthesized  through a process called transamination.• *Transamination involves the tra...
Dr. Siham Gritly   57
• Amino acids can be transaminated to form  alanine from pyruvate• *the alanine is transported to the liver as  primary su...
Diseases associated with protein     Sickle Cell Compared  with Normal Red Blood Cell             Dr. Siham Gritly      59
• sickle-cell anemia: a hereditary form of anemia• characterized by abnormal sickle- or crescent-shaped  red blood cells. ...
Protein-Energy Malnutrition           Dr. Siham Gritly   61
• Adult Bone Loss (Osteoporosis• Cancer• Heart disease                    Dr. Siham Gritly   62
Protein synthesis• *For synthesis of protein all amino acids should be  present or available at the same time (essential a...
• *DNA & RNA are composed of ribose  (pentose sugar) or deoxyribose, phosphoric  acid and nitrogenous base (purine and  py...
• This process of messenger RNA being made  from a template of DNA is known as  transcription.• This process of messenger ...
Protein break down (catabolism)• *any amounts above the needed amino acids  for synthesis of tissues are metabolized.• *am...
Lab technique for studying protein purification,                structure and function• Proteins may be purified from othe...
References• Murry K. Robert, Granner K. daryl, Mayes A. peter, Rodwell  W. Victor (1999). Harpers Biochemistry. Appleton a...
•   Michael W King, PhD | © 1996–2012 themedicalbiochemistrypage.org, LLC | info    @ themedicalbiochemistrypage.org•   D....
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2 amino acids and proteins lecture 2

  1. 1. Principle of Biochemistry2-Amino Acids and Proteins Course code: HFB324 Credit hours: 3 hours Dr. Siham Gritly Dr. Siham Gritly 1
  2. 2. Terms should be learned• Protein; molecule consisting of one or more polypeptide chains• amino acid; an amino group and a carboxylic acid group attached to an ―alpha‖ carbon (α-C); a hydrogen and a small organic group (e.g., —H, — CH3, —CH2OH), called an R-group, are also attached to the α-C• Amphoteric; organic substance that acts as both an acid and a base• chiral compound; molecule that cannot be superimposed on its mirror image Dr. Siham Gritly 2
  3. 3. • Enantiomers; two organic compounds that are are mirror images; these compounds contain one or more chiral carbons• L-amino acid; stereoisomeric form of amino acids found in proteins• N-terminus; (of a protein) the free amino end• peptide bond; linkage between the amino group of one amino acid and the carboxyl group of another amino acid• peptide or polypeptide; a polymer chain of three or more amino acids Dr. Siham Gritly 3
  4. 4. • R-group; (of an amino acid) one of twenty (or more) different organic groups bonded to the alpha carbon• Stereoisomers; molecules with the same chemical formulae; they differ only in the way the different attached groups are oriented in space• Zwitterions; ion with a positive and a negative charge• Chirality describes the ability of a molecule to rotate the plane of polarized light either to the right (dextrorotatory) or to the left (levorotatory Dr. Siham Gritly 4
  5. 5. Composition and nature of proteins;• Proteins are complex organic compound found in animal and plant tissues.• The protein molecules are nitrogen-containing amino acids, in addition to carbon, oxygen, and hydrogen.• some of which are essential in the sense that humans cannot make them internally Dr. Siham Gritly 5
  6. 6. Protein functions 1-Structural function• -Structural function Component of all cell membranes• Component of cytoplasm "cytoskeleton"• Component of movement or contractile structures, such as muscle,• Component of hair, nails horns, etc. (Keratin is the main protein of these substances) Dr. Siham Gritly 6
  7. 7. Protein functions 2-Metabolic functions• 1-enzymatic function• Most specialized proteins with catalytic activity.• All chemical reactions of organic biomolecules in cells are catalyzed by enzymes• Enzymes mainly consist of proteins. Dr. Siham Gritly 7
  8. 8. • 2-hormones (Regulatory Proteins)• Help regulate cellular or physiological activity.• The cellular response to many hormonal signals is often mediated by a class of GTP- binding proteins called G proteins. Dr. Siham Gritly 8
  9. 9. • G proteins are important signal transduction molecules in cells• transmitting chemical signals originating from outside a cell into the inside of the cell.• G proteins activity is regulated by factors that control their ability to bind to and hydrolyze guanosine triphosphate (GTP) to guanosine diphosphate (GDP). Dr. Siham Gritly 9
  10. 10. • 3-Immune function (Defense Proteins)• Defend organisms against invasion by other species or protect them• Immunoglobulin or antibodies, are made by the lymphocytes of vertebrates and can recognize & precipitate or neutralize invading bacteria• Fibrinogen and thrombin are blood clotting proteins Dr. Siham Gritly 10
  11. 11. • 4-Acid base balance buffering agent• Buffers ; are compounds that recover or (improve) a change in pH that occur in response to the addition of alkali or acid to the solution or; A Buffers are substances that can bind protons• Intracellular fluids; protein have the most buffering effect due to its high concentration in the blood.• Less concentration of protein such as albumin in blood causes osmotic pressure in blood plasma decrease and thus fluid leak out into interstitial spaces causing edema or swelling Dr. Siham Gritly 11
  12. 12. edema or swelling Dr. Siham Gritly 12
  13. 13. • Protein molecules possess basic and acidic groups (Amphoteric molecules )which act as H+ acceptors or donors respectively if H+ is added or removed.• A solution with a high hydrogen ion concentration has a low pH and is therefore more acidic,• whereas a solution with a low hydrogen ion concentration has a high pH and is more alkaline Dr. Siham Gritly 13
  14. 14. • Protein buffer: COOH (acid) of amino acid can lose H+ (COO-)• NH2 (amine) of amino acid can gain H+ (NH3+) (buffering effect) Dr. Siham GritlyLysine structure 14
  15. 15. • 5-transport• Bind and carry molecules or ions to organs in the blood plasma.• Lipoproteins in blood plasma carries lipids from the live to other organs Dr. Siham Gritly 15
  16. 16. • 6-Energy sources• any amounts above the needed amino acids for synthesis of tissues are metabolized and degraded.• *The amino group of amino acid is converted to urea in the liver and excreted in urine through urea cycle.• *carboxylic group of amino acids are converted to glucose and enter glycolysis pathway for energy production. Dr. Siham Gritly 16
  17. 17. 7-Nutrient and Storage Proteins• Seeds of many plants store nutrient proteins required for the growth of the germinating seedlings.• Ovalbumin, the major protein of egg white, and casein the major protein of milk are examples of nutrient proteins Dr. Siham Gritly 17
  18. 18. Denaturation of proteins• Denaturation is the breakdown of all covalent bonds causing change in shape and thus loss of function.• Denaturation is due to• -pH• -temperature• -salt concentration• alcohol• heavy metals Dr. Siham Gritly 18
  19. 19. Protein structure Each protein has a unique shape or conformation. all proteinsare composed exclusively of subunits of amino acids, which join together in long chains called polypeptides that fold or coil into the unique shape of the functional protein Dr. Siham Gritly 19
  20. 20. 1-Primary structure of proteinsamino acids sequences• The primary structure of a protein simply consists of its linear sequence of amino acids; for example, "alanine-glycine-tryptophan- serine-glutamate-asparagine-glycine-lysine-… Dr. Siham Gritly 20
  21. 21. 2-Secondary structure• As peptide bonds are formed, aligning the amino acids, hydrogen bonds form between different amino acids in the chain.• This bonding coils the polypeptide into the secondary structure of the protein, most commonly the alpha helix,• The α-helix coils at every 4th amino acid. Dr. Siham Gritly 21
  22. 22. 2-Secondary structureThe α-helix coils of protein Dr. Siham Gritly 22
  23. 23. Pleated Proteinthe polypeptide have portions that lie parallel to each other (held by hydrogenbonds) instead of in the alpha helix, in which the amino acids’ hydrogen bonds form a pleated structure. Fibrous proteins have significant pleated structures Dr. Siham Gritly 23
  24. 24. 3-Tertiary Structure of protein• the side chains (the R groups) of amino acids may fold independently into a functional unit called the domain.• Domains are connected by the rest of the polypeptide.• The folding of a protein into its domains is related to the hydrophilic or hydrophobic properties of its amino acids.• Domain formation is part of the tertiary structure or proteins. globular shape (globulin) Dr. Siham Gritly 24
  25. 25. Tertiary Structure of protein Dr. Siham Gritly 25
  26. 26. • 5 kind of bonds stabilize tertiary structure• 1-van der Waals interaction (between neighboring atoms) Van der Waals forces include attractions and repulsions between atoms, molecules, and surfaces• 2-H-bonds within the chains or between chains Dr. Siham Gritly 26
  27. 27. • 3-hydrophobic interactions (between non polar)• 4-ionic interactions (between oppositely charged groups)• 5-disulphide linkages, the SH groups of two neighboring cysteines form –s=s bond known as disulphide linkage. (covalent bond) Dr. Siham Gritly 27
  28. 28. Amino acid Cysteine disulphide linkages composed of two cysteines linked by a disulfide bond Amino acid Cysteinetwo cysteines linked by a disulfide bond Dr. Siham Gritly 28
  29. 29. 4-Quaternary Protein Structurethe structure formed by several protein molecules (polypeptide chains), usually called protein subunits• If two or more polypeptide chains join in aggregate, they form a quaternary structure, such as in the protein molecule, hemoglobin.• Often quaternary proteins are complexed with a different molecule, often a mineral. Hemoglobin contains iron, for example. Dr. Siham Gritly 29
  30. 30. 4-Quaternary Protein Structure Haemoglobin structure Dr. Siham Gritly 30
  31. 31. Amino acidthe building block of proteins Dr. Siham Gritly 31
  32. 32. Amino Acid General structure of amino acid The carbon atom next to the carboxyl group is called the α carbon and amino acids with a side-chain bonded to this carbonare referred to as alpha amino acids. These are the most common form found in nature. Lysine structure Dr. Siham Gritly 32
  33. 33. Amino acids• Amino acids contain Carbon, Hydrogen, Oxygen, Nitrogen, and sometimes Sulfur• Amino acids have two function groups (both of which are typically in the ionized form)• 1- NH2 Amino functional group• 2-COOH Carboxyl functional group• Both functional groups attach to a specific carbon, the alpha α carbon, of the carbon chain. The third bonding site of the alpha carbon is typically Hydrogen. Dr. Siham Gritly 33
  34. 34. • The alpha carbon will have at its fourth bonding site a side chain, or R group which gives the amino acid its unique structure and properties.• There are 20 + different amino acids in protein. All have a common structure except for the R group. Dr. Siham Gritly 34
  35. 35. • Some amino acids have R groups that are polar (hydrophilic), interact with water at physiological pH (O, N)• some R groups are nonpolar (and hydrophobic C, H),• some have acidic side chains pKa < the physiological pH 7.4. (generally with a negative charge) and some are basic pKa > the physiological pH 7.4• pKa acid-ionization constant or acidity constant• measure of the strength of an acid in solution Dr. Siham Gritly 35
  36. 36. • Some with Amino Acids with Aliphatic R- Groups nonpolar and hydrophobic (Hydrophobicity increases with increasing number of C atoms in the hydrocarbon chain)• Aromatic Amino Acids with benzene ring are relatively nonpolar. aromatic amino acids absorb ultraviolet light. Dr. Siham Gritly 36
  37. 37. • • Amino acids are joined together by a dehydration synthesis of amino/carboxyl groups forming a peptide bond. Dr. Siham Gritly 37
  38. 38. α-Amino Acids structure Found in ProteinsBackbone of the amino acids is red, R-groups are blackreference; Michael W King, PhD | ©996–2012 themedicalbiochemistrypage.org, LLC| info @ themedicalbiochemistrypage.org pK1 pK R Amino pK2Q Acid Symbol Structure* (COO H) (NH2) Grou p Amino Acids with Aliphatic R-Groups nonpolar and hydrophobic (C )Glycine Gly – G 2.4 9.8Alanine Ala – A 2.4 9.9 Valine Val – V 2.2 9.7 Dr. Siham Gritly 38
  39. 39. α-Amino Acids Found in Proteins Backbone of the amino acids is red, R-groups are blackreference; Michael W King, PhD | ©996–2012 themedicalbiochemistrypage.org, LLC | info @ themedicalbiochemistrypage.orgLeucin Leu 2.3 9.7 e –LIsoleuci Ile – 2.3 9.8 ne I Non-Aromatic Amino Acids with Hydroxyl R-Groups Ser –Serine 2.2 9.2 ≈13 S Dr. Siham Gritly 39
  40. 40. α-Amino Acids Found in ProteinsBackbone of the amino acids is red, R-groups are blackreference; Michael W King, PhD | ©996–2012 themedicalbiochemistrypage.org, LLC | info @ themedicalbiochemistrypage.org Threonine Thr – T 2.1 9.1 ≈13 Amino Acids with Sulfur-Containing R-Groups nonpolar and hydrophobic Cysteine Cys – C 1.9 10.8 8.3Methionine Met – M 2.1 9.3 Acidic Amino Acids and their Amides Acidic Amino Acids and their Amides Acidic amino acids are polar and negatively charged at physiological pH. Both acidic amino acids have a second carboxyl group hydrophilicAspartic Acid Asp – D 2.0 9.9 3.9 Dr. Siham Gritly 40
  41. 41. α-Amino Acids Found in Proteins Backbone of the amino acids is red, R-groups are blackreference; Michael W King, PhD | ©996–2012 themedicalbiochemistrypage.org, LLC | info @ themedicalbiochemistrypage.orgAsparagin Asn – N 2.1 8.8 eGlutamic Glu – E 2.1 9.5 4.1 AcidGlutamine Gln – Q 2.2 9.1 Dr. Siham Gritly 41
  42. 42. α-Amino Acids Found in Proteins Backbone of the amino acids is red, R-groups are blackreference; Michael W King, PhD | ©996–2012 themedicalbiochemistrypage.org, LLC | info @ themedicalbiochemistrypage.org Basic amino acidsArginine Arg – R 1.8 9.0 12.5 Lysine Lys – K 2.2 9.2 10.8Histidine His – H 1.8 9.2 6.0 Dr. Siham Gritly 42
  43. 43. α-Amino Acids Found in Proteins Backbone of the amino acids is red, R-groups are black reference; Michael W King, PhD | ©996–2012 themedicalbiochemistrypage.org, LLC | info @ themedicalbiochemistrypage.org Amino Acids with Aromatic Rings cyclic side groups (benzene ring)Phenylalanine Phe – F 2.2 9.2 Tyrosine Tyr – Y 2.2 9.1 10.1 Tryptophan Trp – W 2.4 9.4 Dr. Siham Gritly 43
  44. 44. α-Amino Acids Found in Proteins Backbone of the amino acids is red, R-groups are blackreference; Michael W King, PhD | ©996–2012 themedicalbiochemistrypage.org, LLC | info @ themedicalbiochemistrypage.org Imino AcidsProline Pro – P 2.0 10.6 Dr. Siham Gritly 44
  45. 45. The amino acids found in proteins have a common stereochemistry Optical Properties of the Amino Acids Isomerism• In organic chemistry, this stereochemistry is referred to as L (for levo, meaning left).• A tetrahedral carbon atom with 4 distinct constituents is said to be chiral• Chirality is the ability of a molecule to rotate the plane of polarized light either to the right (dextrorotatory) or to the left (levorotatory). Dr. Siham Gritly 45
  46. 46. • All of the amino acids in proteins exhibit the same steric configuration as L-glyceraldehyde• the amino group is always to the left side of the alpha carbon, Thus, the amino acids found in proteins are L-alpha amino acids• D-amino acids are never found in proteins, although they exist in nature. D-amino acids are often found in polypetide antibiotics Dr. Siham Gritly 46
  47. 47. Acid-Base Properties of the Amino Acids• The α-COOH and α-NH2 groups in amino acids are capable of ionizing (as are the acidic and basic R- groups of the amino acids). As a result of their ionizability the following ionic equilibrium reactions may be written:• R-COOH <——> R-COO– + H+• R-NH3+ <——> R-NH2 + H+• The equilibrium reactions, demonstrate that amino acids contain at least two weakly acidic groups. Dr. Siham Gritly 47
  48. 48. the carboxyl group is stronger acid than the amino group. At physiological pH (around 7.4) the carboxyl group will be unprotonated and the amino group will be protonated.An amino acid with no ionizable R-group would be electrically neutral at this pH. This species is termed a zwitterion. An amino acid in its (1) un-ionized and (2) zwitterionic forms Dr. Siham Gritly 48
  49. 49. • Carboxylic acid groups (−CO2H) can be deprotonated to become negative carboxylates (−CO2− ),• and α-amino groups (NH2−) can be protonated to become positive α-ammonium groups (+NH3−).•• Dr. Siham Gritly 49
  50. 50. Amino acid and peptide linkage Dr. Siham Gritly 50
  51. 51. Peptide linkageamino acids are the structural units of the body protein. They are all α amino-carboxylic acids. All amino acids join together to form Peptide link. Peptide bond is formed by condensation reaction and broken by hydrolysis Dr. Siham Gritly 51
  52. 52. Peptide linkage All peptides and polypeptides are polymers of α- amino acids• *A protein starts as a chain of amino acids, called a polypeptide• *Amino acids are joined by the peptide bond, via dehydration synthesis to form the polypeptide• *The polypeptide chain is referred to as the primary structure of the protein. Dr. Siham Gritly 52
  53. 53. • *The specific amino acids in the polypeptide chain will determine its configuration, or shape, and therefore, its function.• one amino acid substitution in the bonding sequence of a polypeptide can alter the final proteins shape and ability to function Dr. Siham Gritly 53
  54. 54. Essential and non essential amino acids Essential NonessentialIsoleucine AlanineLeucine AsparagineLysine Aspartic AcidMethionine Cysteine*Phenylalanine Glutamic AcidThreonine Glutamine*Tryptophan Glycine* Dr. Siham Gritly 54
  55. 55. Essential NonessentialValine Proline* Selenocysteine* Serine* Tyrosine* Arginine* Histidine* Ornithine* Taurine* Dr. Siham Gritly 55
  56. 56. • *Nonessential amino acids can be synthesized through a process called transamination.• *Transamination involves the transfer of an amino acid group from 1 amino acid to a carbon skeleton to form a new amino acid. Dr. Siham Gritly 56
  57. 57. Dr. Siham Gritly 57
  58. 58. • Amino acids can be transaminated to form alanine from pyruvate• *the alanine is transported to the liver as primary substrate for gluconeogenesis• *this process known as glucose-alanine cycle Dr. Siham Gritly 58
  59. 59. Diseases associated with protein Sickle Cell Compared with Normal Red Blood Cell Dr. Siham Gritly 59
  60. 60. • sickle-cell anemia: a hereditary form of anemia• characterized by abnormal sickle- or crescent-shaped red blood cells. Sickled cells interfere with oxygen transport and blood flow.• Symptoms are precipitated by dehydration and insufficient oxygen (as may occur at high altitudes) and include hemolytic anemia (red blood cells burst), fever, and severe pain in the joints and abdomen.• gene expression: the process by which a cell converts• the genetic code into RNA and protein. Dr. Siham Gritly 60
  61. 61. Protein-Energy Malnutrition Dr. Siham Gritly 61
  62. 62. • Adult Bone Loss (Osteoporosis• Cancer• Heart disease Dr. Siham Gritly 62
  63. 63. Protein synthesis• *For synthesis of protein all amino acids should be present or available at the same time (essential amino acids). Synthesis or building of body proteins controlled by genetic material found in every cell.• *the genetic material found in the nucleus of the cell is Deoxyribose Nucleic Acid (DNA)• *the material DNA is used for synthesis of Ribose Nucleic Acids (RNA).• *there are different forms of RNA, such as mRNA which carries information to the cytoplasm where the protein are synthesized. Dr. Siham Gritly 63
  64. 64. • *DNA & RNA are composed of ribose (pentose sugar) or deoxyribose, phosphoric acid and nitrogenous base (purine and pyrimidine)• *in cytoplasma RNA moleculs tRNA direct the amino acids to correct position with the mRNA to built peptide chain and thus formation of body proteins.• The coming lectures the discussion will be in more details Dr. Siham Gritly 64
  65. 65. • This process of messenger RNA being made from a template of DNA is known as transcription.• This process of messenger RNA directing the sequence of amino acids and synthesis of proteins is known as translation. Dr. Siham Gritly 65
  66. 66. Protein break down (catabolism)• *any amounts above the needed amino acids for synthesis of tissues are metabolized.• *amino acids have both amino group and carboxylic group. The amino group of amino acid is converted to urea in the liver and excreted in urine through urea cycle.• *carboxylic group of amino acids are converted to glucose and enter glycolysis pathway for energy. Dr. Siham Gritly 66
  67. 67. Lab technique for studying protein purification, structure and function• Proteins may be purified from other cellular components using a variety of techniques;• such as ultracentrifugation,• precipitation,• electrophoresis, and chromatography;• Methods commonly used to study protein structure and function include; immunohistochemistry,• site-directed mutagenesis,• nuclear magnetic resonance• mass spectrometry Dr. Siham Gritly 67
  68. 68. References• Murry K. Robert, Granner K. daryl, Mayes A. peter, Rodwell W. Victor (1999). Harpers Biochemistry. Appleton and Lange , twenty fifth edition• Heymsfield, SB.; Olafson RP.; Kutner MH. and Nixon DW. 1979. A radiographic method of quantifying protein-calorie under nutrition American Journal of Clinical Nutrition, 32: 693-702• Chang, Raymond (2007). Chemistry, Ninth Edition. McGraw- Hill. pp. 52.• Sareen S. Gropper, Jack L.Smithh and James L. Groff; 2007. advanced Nutrition and Human Metabolism, fifth ed. Wadsworth CENGAGE learning Dr. Siham Gritly 68
  69. 69. • Michael W King, PhD | © 1996–2012 themedicalbiochemistrypage.org, LLC | info @ themedicalbiochemistrypage.org• D. Voet, J. G. Voet, Biochemistry, second edition ed., John Wiley &• Sons, New York, 1995• Sareen Gropper, Jack Smith and James Groff, Advanced Nutrition and Human Metabolism, fifth ed. WADSWORTH• Melvin H Williams 2010; Nutrition for Health, Fitness and Sport. 9th ed, McGraw Hill•• Heymsfield, SB.; Baumgartner N.; Richard and Sheau-Fang P. 1999. Modern Nutrition in Health and Disease; Shils E Maurice, Olson A. James, Shike Moshe and Ross A. Catharine eds. 9th edition• Guyton, C. Arthur. 1985. Textbook of Medical Physiology. 6th edition, W.B. Company Dr. Siham Gritly 69
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