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Trp

E4P. Trp. Tryptophan. Tryptophan. ATP: Histidine. Remember the cost of glutamate.  KG + NADPH + NH 3 + ATP ---> glutamate + NADP + + ADP + P i. Making glycine, alanine, aspartate, glutamate costs 1 NADPH and 1 ATP. Making glutamine costs an additional ATP

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Trp

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  1. E4P Trp

  2. Tryptophan Tryptophan ATP: Histidine

  3. Remember the cost of glutamate KG + NADPH + NH3 + ATP ---> glutamate + NADP+ + ADP + Pi Making glycine, alanine, aspartate, glutamate costs 1 NADPH and 1 ATP Making glutamine costs an additional ATP Making asparagine costs an additional 2ATP

  4. KG + NADPH + NH3 + ATP ---> glutamate + NADP+ + ADP + Pi KG + 3NADPH + NH3 + 2ATP ---> proline + 3NADP+ + 2ADP + 2Pi

  5. Proline degradation Proline Pyrroline-5-carboxylate

  6. Non-enzymatic

  7. Glutamate semialdehyde dehydrogenase Glutamate semialdehyde Glutamate

  8. So….Proline = glutamate If: Glu = -ketoglutarate + NADPH + NH3 Then: Pro = -ketoglutarate + NADPH + NH3 If: -ketoglutarate = 4 NADH + 2 GTP + 2 FADH2 + NADPH Then: Pro = 4 NADH +2 GTP + 2 FADH2 + 2 NADPH + NH3 If: NADH = 3 ATP GTP = ATP FADH2 = 2 ATP NH3 = -2 ATP Then: Pro = 16 ATP + 2 NADPH

  9. Arginine Degradation Arginase Arginase

  10. Ornithine--aminotransferase

  11. Ornithine--aminotransferase

  12. Ornithine--aminotransferase

  13. Glutamate semialdehyde dehydrogenase Glutamate semialdehyde Glutamate

  14. KG + NADPH + NH3 + ATP ---> glutamate + NADP+ + ADP + Pi KG + Acetyl-CoA + 4NADPH + 3NH3 + 7ATP + CO2 ---> arginine + 4NADP+ + 6ADP + 1AMP+ 6Pi + 1PPi

  15. So…Arg = Glutamate + NADPH + NH3 If: Glu = -ketoglutarate + NADPH + NH3 Then: Arg = -ketoglutarate + 2 NADPH + 2 NH3 If: -ketoglutarate = 4 NADH + 2 GTP + 2 FADH2 + NADPH Then: Arg = 4 NADH +2 GTP +2 FADH2 + 3 NADPH + 2NH3 If: NADH = 3 ATP GTP = ATP FADH2 = 2 ATP NH3 = -2 ATP Then: Arg = 14 ATP + 3 NADPH What is the problem with arginine degradation?

  16. alpha-ketoglutarate glutamate glutamate semialdehyde Control point proline N-acetylglutamate semialdehyde arginine

  17. Remember the cost of aspartate oxaloacetate + NADPH + NH3 + ATP ---> aspartate + NADP+ + ADP + Pi

  18. oxaloacetate + 4NADPH + 2NH3 + 3ATP + pyruvate + succinyl-CoA ---> lysine + 4NADP+ + 3ADP + 3Pi + CO2

  19. This is this is not the only way to make lysine Homocitrate synthase Homoaconitase Homoisocitrate DH Homoaconitase -ketoadipate

  20. -KG + acetyl-CoA + + 2NH3 + 2NAD+ + 4ATP + 4NADPH ---> Lysine + CO2 + 2NADH + 4NADP+ + 4ADP + 4Pi

  21. NADPH Lysine Degradation

  22. NAD+ -ketoadipate

  23. NADH FADH2

  24. NADH

  25. So…Lysine = NADH + -ketoadipate + 2 NH3 If: -ketoadipate = 2 NADH + FADH2 + 2 Acetyl-CoA Then: Lys = 3 NADH + FADH2 + 2 Acetyl-CoA + 2 NH3 If: Acetyl-CoA = 3 NADH + FADH2 + GTP Then: Lys = 9 NADH + 3 FADH2 + 2 GTP + 2 NH3 If GTP = ATP, NADH = 3 ATP FADH2 = 2 ATP and NH3 = -2 ATP Then: Lys = 35 ATP

  26. oxaloacetate + 3NADPH + NH3 + 3ATP ---> threonine + 3NADP+ + 3ADP + 3Pi

  27. Threonine can be degraded in three ways (1) Threonine dehydrogenase pathway Threonine Dehydrogenase

  28. Must break C-C bond on an amino acid and stabilize a carbanion

  29. 2-amino--ketobutyrate lyase

  30. What happens to the glycine? Glycine Cleavage System: trifunctional enzyme STEP1: decarboxylation of glycine

  31. STEP 2: formation of N5,N10-methylene-THF THF N5,N10-methylene-THF

  32. STEP 3: regeneration of catalytic site NADH NAD+

  33. There is another pathway of glycine degradation From glycine cleavage system Combine the glycine cleavage system with a reverse of the serine hydroxymethyltransferase rxn

  34. So…2 glycine = 1 serine + NADH + NH3

  35. If: 2 Gly = serine + NADH + NH3 If: Ser = pyruvate + NH3 Then: 2 Gly = pyruvate + NADH + 2 NH3 If: Pyruvate = 4 NADH + GTP + FADH2 Then: 2 Gly = 5 NADH + GTP + FADH2 + 2 NH3 If: NADH = 3 ATP GTP = ATP FADH2 = 2 ATP NH3 = -2 ATP Then: 2 Gly = 14 ATP, 1 Gly = 7 ATP

  36. So… Thr = Gly + Acetyl-CoA + NADH If: glycine is degraded by glycine cleavage system you get 1 N5,N10-methylene tetrahydrofolate, NH3 and NADH Then: Thr = N5,N10-THF + NH3 + 2 NADH + Acetyl-CoA If Acetyl-CoA = 3 NADH + GTP + FADH2 Then: Thr = N5,N10-THF + NH3 + 5 NADH + GTP + FADH2 If NADH = 3 ATP GTP = ATP FADH2 = 2 ATP NH3 = -2 ATP Then: Thr = N5,N10-THF + 16 ATP

  37. If: 2 Thr are degraded to 2 Gly Then: 2 Thr = 2 Gly + 2 NADH + 2 Acetyl-CoA If: 1 Gly = N5,N10- THF + 1 NH3 + 1 NADH by glycine cleavage system And 1 Gly + N5,N10-methylene tetrahydrofolate = serine by serine hydroxymethyltransferase Then: 2 Thr = 1 NH3 + 3 NADH + 2 Acetyl-CoA + serine If: Ser = pyruvate + NH3 Then: 2 Thr = 2 NH3 + 3 NADH + 2 Acetyl-CoA + pyruvate If: Acetyl-CoA = 3 NADH + GTP + FADH2 Pyruvate = 4 NADH +GTP + FADH2 Then: 2 Thr = 2 NH3 + 13 NADH + 3GTP + 3 FADH2 If: GTP = ATP, NADH = 3 ATP FADH2 = 2 ATP and NH3 = -2 ATP Then: 2 Thr = 44 ATP, Thr = 22 ATP

  38. (2) Threonine can be degraded by serine hydroxymethyltransferase

  39. What happens to acetaldehyde: can’t be put onto THF NAD+ NADH Acetaldehyde dehydrogenase Thr = glycine + Acetyl-CoA + NADH

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