1. Metabolism of amino acids - exercise -
Vladimíra Kvasnicová

2. Choose essential amino acids
Asp, Glu
Val, Leu, Ile
Ala, Ser, Gly
Phe, Trp

3. Choose essential amino acids
Asp, Glu
Val, Leu, Ile
Ala, Ser, Gly
Phe, Trp

4. „10“ Essential amino acids branched chain: Val, Leu, Ile
basic: His, Arg, Lys
aromatic: Phe (→ Tyr), Trp
sulfur-containing: Met (→ Cys)
other: Thr

5. Choose amino acids from which the other amino acid can be synthesized in a human body
valine → leucine
aspartate → asparagine
phenylalanine → tyrosine
methionine + serine → cysteine

6. Choose amino acids from which the other amino acid can be synthesized in a human body
valine → leucine leucine is the essential AA
aspartate → asparagine
phenylalanine → tyrosine
methionine + serine → cysteine

7. needs glutamine as –NH2 group donor
Synthesis of
ASPARAGINE
needs glutamine as –NH2 group donor
(it is not ammonia as in the Gln synthesis)
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, ISBN 0‑471‑15451‑2

8. Synthesis of Tyr from Phe
The figure is from (Jan 2007)

9. Synthesis of Cys from Met and Ser
The figure is from (Jan 2007)

10. The amino acids can be formed from the citrate cycle intermediates in a human body
-ketoglutarate → glutamate
succinyl-CoA → isoleucine
oxaloacetate → aspartate
malate → threonine

11. The amino acids can be formed from the citrate cycle intermediates in a human body
-ketoglutarate → glutamate
succinyl-CoA → isoleucine Ile is the essential AA
oxaloacetate → aspartate
malate → threonine Thr is the essential AA

12. Amphibolic character of citrate cycle
The figure is from (Dec 2006)

13. The compound(s) can be synthesized from the amino acid
tyrosine → serotonin
serine → ethanolamine
tryptophan → catecholamines
cysteine → taurine

14. The compound(s) can be synthesized from the amino acid
tyrosine → serotonin Tyr → catecholamines
serine → ethanolamine formed by decarboxylation
tryptophan → catecholamines Trp → serotonin
cysteine → taurine

15. taurin is used in conjugation reactions in the liver – it is bound to hydrophobic substances to increase their solubility (e.g. conjugation of bile acids)
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, ISBN 0‑471‑15451‑2

16. If the amino acid is metabolised the substance is formed:
methionine gives homocysteine
serine gives glycine and folic acid derivative: methylene tetrahydrofolate
glutamine releases ammonia
some amino acides can be degraded to acetoacetate

17. If the amino acid is metabolised the substance is formed:
methionine gives homocysteine
serine gives glycine and folic acid derivative: methylene tetrahydrofolate
glutamine releases ammonia
some amino acides can be degraded to acetoacetate = one of ketone bodies

18. Regeneration of Met (vitamins: folate+B12) B12
The figure is from (Jan 2007)

19. Synthesis of serine and glycine
glycolysis
The figure is from (Jan 2007)

20. Choose products of the transamination reactions
alanine → pyruvate
glutamate → 2-oxoglutarate
aspartate → oxaloacetate
phenylalanine → tyrosine

21. Choose products of the transamination reactions
alanine → pyruvate
glutamate → 2-oxoglutarate
aspartate → oxaloacetate
phenylalanine → tyrosine it is not transamination

22. Transamination reaction ! REVERSIBLE !
enzymes: amino transferases
coenzyme: pyridoxal phosphate (vit. B6 derivative)
The figure is from (Jan 2007)

23. Amino transferases important in medicine („transaminases“)
alanine aminotransferase (ALT = GPT)
aspartate aminotransferase (AST = GOT)
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, ISBN 0‑471‑15451‑2

24. Amino nitrogen released from carbon sceletons of AAs can be transported in blood as
NH4+
alanine
glutamine
urea

25. Amino nitrogen released from carbon sceletons of AAs can be transported in blood as
NH4+ physiologically up to 35 µmol/l (NH3 + H + NH4+)
alanine formed by transamination from pyruvate
glutamine the most important transport form of –NH2
urea it is the end product of degradation of amino nitrogen (liver → kidneys → urine)

26. Transport of amino nitrogen from degraded muscle proteins
products excreted with urine
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, ISBN 0‑471‑15451‑2

27. Glucose-alanine cycle
alanine transfers both the carbon sceleton for gluconeogenesis and –NH2 group
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, ISBN 0‑471‑15451‑2

28. GLUTAMINE
= the most important transport form af amino nitrogen in blood
it transfers two amino groups released by degradation of AAs
glutamine synthetase
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, ISBN 0‑471‑15451‑2

29. Choose glucogenic amino acids
alanine
lysine
leucine
glutamine

30. Choose glucogenic amino acids
alanine
lysine
leucine
glutamine

31. 7 degradation products of AAs
pyruvate  Gly, Ala, Ser, Thr, Cys, Trp
oxaloacetate  Asp, Asn
-ketoglutarate  Glu, Gln, Pro, Arg, His
succinyl-CoA  Val, Ile, Met, Thr
fumarate  Phe, Tyr
acetyl-CoA  Ile
acetoacetyl-CoA  Lys, Leu, Phe, Tyr, Trp
glucogenic AAs
ketogenic AAs

32. Glutamate dehydrogenase (GMD)
catalyzes conversion of Glu to oxaloacetate
is found in mitochondria of hepatocytes
produces ammonia
needs pyridoxal phosphate as a coenzyme

33. Glutamate dehydrogenase (GMD)
catalyzes conversion of Glu to oxaloacetate
is found in mitochondria of hepatocytes
produces ammonia
needs pyridoxal phosphate as a coenzyme

34. GLUTAMATE DEHYDROGENASE
removes amino group from carbon sceleton of Glu in the liver
1. –NH2 from AAs was transfered by transamination → Glu
2. free ammonia is released by oxidative deamination of Glu
The figure is from (Jan 2007)

35. Choose correct statement(s) about metabolism of amino acids
alanine aminotransferase (ALT) transforms pyruvate to alanine
aspartate aminotransferase (AST) transforms aspartate to -ketoglutarate
glutamine synthetase transforms glutamate to glutamine
glutaminase catylyzes conversion of glutamine to ammonia and -ketoglutarate

36. Choose correct statement(s) about metabolism of amino acids
alanine aminotransferase (ALT) transforms pyruvate to alanine
aspartate aminotransferase (AST) transforms aspartate to -ketoglutarate
glutamine synthetase transforms glutamate to glutamine
glutaminase catylyzes conversion of glutamine to ammonia and -ketoglutarate

37. Amino transferases important in medicine („transaminases“)
alanine aminotransferase (ALT = GPT)
aspartate aminotransferase (AST = GOT)
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, ISBN 0‑471‑15451‑2

38. Glutamine is principal transport form of amino nitrogen
The figure is from (Dec 2006)

39. The amino acids can enter the citrate cycle as the molecules
alanine → → acetyl-CoA
aspartate → oxaloacetate
valine → → succinyl-CoA
glutamine → → -ketoglutarate

40. The amino acids can enter the citrate cycle as the molecules
alanine → → acetyl-CoA
aspartate → oxaloacetate
valine → → succinyl-CoA
glutamine → → -ketoglutarate

41. The entrance of amino acids into the citrate cycle
The figure is from (Jan 2007)

42. Ornithine cycle proceeds only in the liver produces uric acid
includes arginine as an intermediate
produces energy in a form of ATP

43. Ornithine cycle proceeds only in the liver produces uric acid
includes arginine as an intermediate
produces energy in a form of ATP

44. Detoxication of ammonia in the liver
The figure is from (Jan 2007)

45. Interconnection of the urea cycle with the citrate cycle
The figure is from (Jan 2007)

46. In the urea synthesis ammonia reacts with ornithine → citrulline
carbamoyl phosphate synthetase I (= mitochondrial) regulates the cycle
aspartate is used as a –NH2 group donor
urea is formed – it can be used as an energy substrate for extrahepatic tissues

47. In the urea synthesis ammonia reacts with ornithine → citrulline
carbamoyl phosphate synthetase I (= mitochondrial) regulates the cycle
aspartate is used as a –NH2 group donor
urea is formed – it can be used as an energy substrate for extrahepatic tissues

48. Regulation of urea cycle
allosteric regulation + enzyme induction by protein rich diet or by metabolic changes during starvation
regulatory enzyme
activation
inhibition
carbamoyl phosphate synthetase I (= mitochondrial)
N-acetylglutamate
N-acetylglutamate synthetase
arginine
Urea synthesis is inhibited by acidosis – HCO3- is saved