S.i.m.p.l.e. proteins-3 En seminar DA.ppt

Simple proteins-3 En seminar DA.ppt

1. Protein metabolism III.
Ammonium detoxification.
Specific pathways of AA metabolism

2. Sources of ammonia
-deamination of amino acids (for example, glutamate dehydrogenase)
-glutaminase
-intestinal bacterial flora
-degradation of purines and pyrimidines

3. Toxicity of ammonia
-Enhances amination of - keto-glutarate to glutamate
-Decreases TCA pool of -keto-glutarate
-Slow down of TCA cycle
-Cellular respiration and ATP formation affected

4. Increased ammonia enhances glutamine formation
This reduces glutamic acid pool of brain cells
Result in decreased formation of inhibitory neurotransmitter
GABA

5. Detoxification of ammonia
Glutamine synthetase
Urea cycle

7. Regeneration of aspartate and energetic cost of the urea cycle
-2 ATP
-2 ATP
+2.5 ATP
Overall balance =4-2.5 = 1.5 ATP
Oxalo-
acetate

8. Glycine
•- donor or active C1 (purine and thymine synthesis).
•- Synthesis of purines (imidazole ring)
•- Synthesis of thymine (methylation)
•- Heme synthesis,
•- Creatine synthesis,
•- Synthesis of glycocholic bile acid,
•- synthesis of glutathione,
•- Neurotransmitter,
•- collagen synthesis

9. Serine
•- donor or active C1 (purine and thymine synthesis).
•- synthesis of phospo- and sphyngolipids,
•- Synthesis of other amino acids: glycine, alanine, cysteine,
•- Serine phosphorylation in proteins
•- Serine proteinases

10. Serine hydroxymethyltransferase

11. Cysteine
•- thiol proteinases,
•- S-S bonds,
•- Glutathione,
•- Taurine (inhibitory neurotransmitter, improves the contractile
activity of the heart, antioxidant, source of sulfuric acid, gives
taurocholic acid). Synthesis of GAG, neutralization of putrefaction and
toxic products.
•- Taurocholic acid.

12. Taurine synthesis

13. Methionine as a methyl group donator

14. Methylation products
•-Choline, phosphatidylcholine, acetylcholine
•Adrenaline,
•Inactivated amines and toxic products,
•L-Cartinitine,
•Creatine,
•Methylated DNA, proteins (histones)

15. Homocysteine formation and utilization

16. Phenylalanine metabolism

17. Synthesis of creatine occurs in kidneys and liver
Creatine and phosphocreatine – biological role

18. 1
2
3
4
5

19. Step 1

20. Step 2
Tyrosine DOPA (dioxyphenylalanine)
BH4 BH2
O2 H2O
Tyrosine hydroxylase
Rate limiting step

21. Step 3
Aromatic amino acid decarboxylase
DOPA dopamine
CO
2
PLP

22. Step 4 Dopamine hydroxylase

23. Step 5 Methyltransferase
SAM SAH

24. Formation of phosphocreatine

25. Creatine kinase

26. Creatinine
dehydration dephosphorylation