Mahmoud BalbaaProfessor of BiochemistryBeirut Arab UniversityMarch 2012
Dynamics of Protein        And Amino Acid MetabolismDietary Proteins         Digestion to Amino Acids                     ...
Digestion of ProteinsStomach: Pepsinogen        Pepsin (max. act. pH 2)                               EnteropeptidaseSmall...
20 Amino Acids
Metabolic Classification of theAmino Acids  •   Essential and Non-essential  • Glucogenic and Ketogenic                   ...
Non-Essential Amino Acids in  Humans Not required in diet Can be formed from α-keto acids by  transamination and subsequ...
Essential Amino Acids in  Humans Required in diet Humans incapable of forming requisite  carbon skeleton          •   Ar...
Glucogenic Amino Acids Metabolized to α-ketoglutarate,    pyruvate, oxaloacetate, fumarate, or    succinyl CoA        Pho...
Ketogenic Amino Acids  Metabolized to acetyl CoA or  acetoacetyl CoA  Animals cannot convert acetyl CoA or  acetoacetyl C...
5. Carbon Atoms     Ketogenic   Glucogenic Both     leucine     serine          isoleucine     lysine      threonine      ...
4. The Urea Cycle11
Urea Formation Occurs primarily in liver; excreted by  kidney Principal method for removing ammonia Hyperammonemia:   ...
Blood Urea Nitrogen Normal range: 7-18 mg./dL Elevated in amino acid catabolism   Glutamate       N-acetylglutamate    ...
5. Carbon Atoms14
Alkaptonuria   • Deficiency of homogentisate dioxygenase   • Urine turns dark on standing      • Oxidation of homogentisic...
Serotonin• Serotonin formed in:   •   Brain (neurotransmitter; regulation of sleep, mood, appetite)   •   Platelets (plate...
Proteins : Classification Solubility   Albumins (s. in water and salt sol.)   Globulins (s. sparingly in water, s. in s...
Proteins : Classification Shape   Globular (albumins, globulins, enzymes)   Fibrous (keratin, myosin, collagen, fibrin)...
• Primary• Secondary• Tertiary• Quarternary
Primary structure Sequence of amino acids Peptide bond Encoded in DNA      DNA          mRNA          protein Determin...
Primary structure
Secondary structure Spatial arrangement of AA chain Most stable structure - low energy:  all -NH groups bond to -CO- gro...
Alpha helix
Beta pleated sheet
Tertiary structure Overall shape and folding pattern of  polypeptide chain Bonds   Disulphidic bridges   Ion interacti...
Tertiary structure                 Acidic proteinase
Quarternary structure More polypeptide chains united by forces  other than covalent bonds   Hydrogen bonds   Ion bonds ...
Quarternary structure
Upcoming SlideShare
Loading in...5
×

Amino acids & proteins

1,845

Published on

Lecture of amino acids and proteins

Published in: Education, Technology, Business
0 Comments
5 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
1,845
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
0
Comments
0
Likes
5
Embeds 0
No embeds

No notes for slide
  • - Proposed by Hans Krebs and Kurt Henseleit in 1932 - Was the first metabolic cycle to be discovered. • Before the citric acid cycle • It is linked to the citric acid cycle. - One of the N atoms comes directly from ammonium ion, the other from aspartate. - The C atom comes from HCO 3 (CO 2 ).
  • - Alanine -
  • Transcript of "Amino acids & proteins"

    1. 1. Mahmoud BalbaaProfessor of BiochemistryBeirut Arab UniversityMarch 2012
    2. 2. Dynamics of Protein And Amino Acid MetabolismDietary Proteins Digestion to Amino Acids Transport in Blood to Cells Protein Synthesis Functional Proteins Amino Acids Protein Degradation In Proteasomes Following Tagging With Ubiquitin Metabolites 2
    3. 3. Digestion of ProteinsStomach: Pepsinogen Pepsin (max. act. pH 2) EnteropeptidaseSmall Intestine: Trypsinogen Trypsin Trypsin cleaves: Chymotrypsinogen to chymotrypsin Proelastase to elastase Procarboxypeptidase to carboxypeptidase Aminopeptidases (from intestinal epithelia) 3
    4. 4. 20 Amino Acids
    5. 5. Metabolic Classification of theAmino Acids • Essential and Non-essential • Glucogenic and Ketogenic 5
    6. 6. Non-Essential Amino Acids in Humans Not required in diet Can be formed from α-keto acids by transamination and subsequent reactions• Alanine • Glycine • Asparagine • Proline • Aspartate • Serine • Glutamate • Cysteine (from Met*) • Glutamine • Tyrosine (from Phe*) * Essential amino acids 6
    7. 7. Essential Amino Acids in Humans Required in diet Humans incapable of forming requisite carbon skeleton • Arginine* • Lysine • Histidine* • Methionine • Isoleucine • Threonine • Leucine • Phenylalanine • Valine • Tryptophan * Essential in children, not in adults 7
    8. 8. Glucogenic Amino Acids Metabolized to α-ketoglutarate, pyruvate, oxaloacetate, fumarate, or succinyl CoA Phosphoenolpyruvate Glucose• Aspartate • Methionine • Alanine• Asparagine • Valine • Serine• Arginine • Glutamine • Cysteine• Phenylalanine • Glutamate • Glycine• Tyrosine • Proline • Threonine• Isoleucine • Histidine • Tryptophan 8
    9. 9. Ketogenic Amino Acids  Metabolized to acetyl CoA or acetoacetyl CoA Animals cannot convert acetyl CoA or acetoacetyl CoA to pyruvate • Isoleucine • Tryptophan • Leucine * • Phenylalanine • Lysine * • Tyrosine • Threonine * Leucine and lysine are only ketogenic 9
    10. 10. 5. Carbon Atoms Ketogenic Glucogenic Both leucine serine isoleucine lysine threonine phenylalanine aspartic acid tryptophan glutamic acid tyrosine asparagine glutamine glycine alanine valine proline histidine arginine methionine cysteine10
    11. 11. 4. The Urea Cycle11
    12. 12. Urea Formation Occurs primarily in liver; excreted by kidney Principal method for removing ammonia Hyperammonemia:  Defects in urea cycle enzymes (CPS, OTC, etc.)  Severe neurological defects in neonates  Treatment:  Stop protein intake  Dialysis  Increase ammonia excretion: Na benzoate, Na phenylbutyrate, L-arginine, L-citrulline 12
    13. 13. Blood Urea Nitrogen Normal range: 7-18 mg./dL Elevated in amino acid catabolism Glutamate N-acetylglutamate CPS-1 activation Elevated in renal insufficiency Decreased in hepatic failure 13
    14. 14. 5. Carbon Atoms14
    15. 15. Alkaptonuria • Deficiency of homogentisate dioxygenase • Urine turns dark on standing • Oxidation of homogentisic acid • Asymptomatic in childhood • Tendency toward arthritis in adulthood 15
    16. 16. Serotonin• Serotonin formed in: • Brain (neurotransmitter; regulation of sleep, mood, appetite) • Platelets (platelet aggregation, vasoconstriction) • Smooth muscle (contraction) • Gastrointestinal tract (enterochromaffin cells - major storage site)• Drugs affecting serotonin actions used to treat: • Depression •Serotonin-selective reuptake inhibitors (SSRI) • Migraine • Schizophrenia • Obsessive-compulsive disorders • Chemotherapy-induced emesis• Some hallucinogens (e.g., LSD) act as serotonin agonists 16
    17. 17. Proteins : Classification Solubility  Albumins (s. in water and salt sol.)  Globulins (s. sparingly in water, s. in salt sol.)  Prolamines (s. in 70-80% ethanol, Arg rich)  Histones (s. in salt sol., basic)  Scleroproteins (insoluble in water and salt sol., Gly, Ala, Pro rich)
    18. 18. Proteins : Classification Shape  Globular (albumins, globulins, enzymes)  Fibrous (keratin, myosin, collagen, fibrin) Function Physical properties  Electrophoretic mobility  Sedimentation (ultracentrifugation)
    19. 19. • Primary• Secondary• Tertiary• Quarternary
    20. 20. Primary structure Sequence of amino acids Peptide bond Encoded in DNA DNA mRNA protein Determines higher structures
    21. 21. Primary structure
    22. 22. Secondary structure Spatial arrangement of AA chain Most stable structure - low energy: all -NH groups bond to -CO- groups by hydrogen bonds  Within a single chain: α -helix  Between two chains: β-pleated sheet o parallel o antiparallel  Special type: collagen helix Also maintained by hydorphobic interactions
    23. 23. Alpha helix
    24. 24. Beta pleated sheet
    25. 25. Tertiary structure Overall shape and folding pattern of polypeptide chain Bonds  Disulphidic bridges  Ion interactions  Hydrophobic interactions  Hydrogen bonds Energically most efficient
    26. 26. Tertiary structure Acidic proteinase
    27. 27. Quarternary structure More polypeptide chains united by forces other than covalent bonds  Hydrogen bonds  Ion bonds  Hydrophobic interactions
    28. 28. Quarternary structure

    ×