Protein and amino acid metabolism

1. Protein and amino acid metabolism

2. Protein-rich products

3. Essential amino acids

valine, leucine, isoleucine,
lysine, methionine, threonine,
tryptophan, phenylalanine
arginine and histidine

4. Proteases

Serine proteases
Cysteine proteases
Aspartic proteases
Metalloproteases
Treonine proteases
Glutamic proteases

5.

Active site
of tripsin
Active site of
chymotripsin

6. HCL secretion

7. Pepsinogen activation

8. The selectivity of pepsin

Enzyme
Pepsin
Splittable peptide
bonds
phenylalanine,
tyrosine, glutamic
acid

9. Trypsinogen activation

10. Activation of intestinal proteases

11. The selectivity of peptidases

Enzyme
Splittable peptide
bonds
Trypsin
Chymotrypsin
lysine, arginine
Elastase
alanine, serine, glycine
Carboxypeptidase A
alanine, leucine, valine
Carboxypeptidase В
lysine, arginine
tryptophan,
phenylalanine, tyrosine

12. Amino acid absorption

13. Transport Catalytic cycle of GGT

14. Conversion of amino acids under the action of intestinal microflora

15. Proteolysis in tissues

16.

Avram Hershko,
Aaron Ciechanover and Irwin Rose
Nobel Prize in Chemistry, 2004

17. Reactions of amino group

Reductive deamination
Hydrolytic deamination
Intramolecular deamination
histidine
urocanic acid

18. Oxidative deamination

19. Transamination

20. Evaluation of transaminase activity

AST
ALT
Alanine + α-ketoglutarate
pyruvate + glutamate

21. Transaminases in human tissues (U/g protein)

Tissues
Heart
Liver
Cerebral cortex
Skeletal muscle
Pancreas
AST
1166
612
1230
357
86
ALT
66
358
8
33
20

22.

АSТ
de Ritis ratio =
АLТ
Myocardial infarction DRr 1,3
Viral hepatitis DRr 1

23. Decarboxylation

24.

thiamine pyrophosphate

25. Decarboxylation

glutamic acid
-aminobutyric acid

26. Oxidative deamination of biogenic amines

R-CH2-NH2 + E-FAD + H2O
R-CHO + NH3 + E-FAD H2
E-FAD H2 + O2 E-FADH2 + H2O2

27. Ammonia neutrralisation

28. Urea cycle. Reactions 1, 2

NH3 + CO2 +2 ATP + H2O
Carbamoylphosphate
synthetase
H2N-CO-OPO3H2 + 2 ADP + H3PO4
Ornithine
transcarbamoilase
Rate-limiting!

29. Urea cycle. Reaction 3

Argininosuccinate
synthetase

30. Urea cycle. Reaction 4

Argininosuccinase

31. Urea cycle. Reaction 5

Rate-limiting!

32.

33. Kwashiorkor

34.

35.

Hereditary disorders
of Urea cycle
Disease
Enzyme
Mode of
inheritance
Clinical
presentations
Blood
metabolites
HyperCarbamoyl Autosomal Coma, and death
ammonemia, phosphate recessive within 24-48 hours
type I
synthetase I
after birth
Gln
Аlа
NH3
HyperOrnithine
ammonemia, carbamoyltype II
transferase
Gln
Аlа
NH3
X-linked
Hypotension,
reduced tolerance
to proteins