orgânica / bioquimica

1. Ciclo de Krebs
Fosforilação Oxidativa
PROFESSORA : ADRIANNE MENDONÇA

2. Funções do Ciclo,
-Gerar ATP, coenzimas reduzidas
-“Gerar” intermediários para vias biossínteses
-Ciclo é estágio final de várias vias

7. Complexo piruvato dehidrogenase

9. TPP ↓ Grupo reativo
↓ Grupo reativo
↓
carbanion
carbanion

14. Acetyl CoA+Oxaloacetate to Citrate
Citrate synthase
Enzyme:
Reaction: Condensation
Acetyl CoA condenses with oxaloacetate first,to form citryl CoA. Then citryl CoA is
hydrolyzed to citrate and CoA.
Prosthetic group: No

15. Citrate to cis-Aconitate
Enzyme: Aconitase
Reaction: Dehydration
Citrate is isomerized to isocitrate by this first dehydration and yields cis-aconitate as an intermediate.
Prosthetic group: Fe-S

16. cis-Aconitate to Isocitrate
Enzyme: Aconitase
Reaction: Hydration
Hydration of cis-aconitate gives the interchange of H atom and OH group from the step 2.
Prosthetic group: Fe-S

17. Isocitrate to alpha-Ketoglutarate
Enzyme: Isocitrate dehydrogenase
Reaction: Oxidative decarboxylation
Dehydrogenation of isocitrate occurs and yields oxalosuccinate as an intermediate.Then
CO2 leaves to have alpha-ketoglutarate.This reaction gives NADH.
Prosthetic group: No

18. alpha-Ketoglutarate to Succinyl CoA
Enzyme: alpha-Ketoglutarate dehydrogenase complex
Reaction: Oxidative decarboxylation
This mechanism is almost as same as the reaction of the oxidative
decarboxylation of pyruvate to acetyl CoA by pyruvate dehydrogenase complex.
This reaction gives one NADH.
Prosthetic group: Lipoic acid, FAD, TPP

19. Succinyl CoA to Succinate
Enzyme: Succinyl CoA synthetase
Reaction: Substrate-level phosphorylation
The thioester bond of succinyl and CoA is an energy rich bond. Thus only this step gives a
high-energy phosphate compound,GTP from the couple reactions of the thioester bond
cleavage and the phosphorylation of GDP.
Prosthetic group:No
GTP + ADP → GDP + ATP

20. Succinate to Fumarate
Enzyme: Succinate dehydrogenase
Reaction: Oxidation
The two hydrogens of succinate leave to an acceptor, FAD. Then this reaction yields fumarate and
FADH2.
Prosthetic group: FAD & Fe-S

21. Fumarato → l-Malato
Fumarase

22. Malate to Oxaloacetate
Enzyme: Malate dehydrogenase
Reaction: Oxidation
Malate is dehydrogenated to form oxaloacetate. The hydrogen acceptor is NAD. So this reaction
yields NADH.
Prosthetic group: No

23. 1 cal~ 4 Joules

24. Note AcetilCoA é na prática queimado no ciclo,
Os intermediários do ciclo não são!!

29. Elementos necessários ao TCA, reações anapleróticas repõem intermediários do Krebs.

30. Repor ciclo para funcionar

32. 

34. Bactérias e plantas

37. 2 Ac CoA + NAD+ + 2 H2O  Succinato + 2 CoA +

39. Fosforilação Oxidativa

41. ∆Go' = -nℑ∆Eo'

43. Fe3+ + e- → Fe2+ 0.771
NO3-+2 H++2 e- → NO2-+H2O
0.421
Cytochrome f( Fe3+)+ e- → cytochrome f(Fe2+)
0.365
Cytochrome a3( Fe3+)+ e- → cytochrome a3(Fe2+) 0.350
Cytochrome a(Fe3+)+ e- → cytochrome a(Fe2+) 0.290
Cytochrome c( Fe3+)+ e - → cytochrome c(Fe2+) 0.254
Cytochrome c1( Fe3+)+ e - → cytochrome c1(Fe2+) 0.220
UQH ⋅ + H1 + e- → UQH2 (UQ=coenzyme Q) 0.190
UQ + 2 H+ + 2 e- → UQH2 0.060
Cytochrome bH(Fe3+) + e - → cytochrome bH(Fe2+) 0.050
Fumarate + 2 H+ + 2 e- → succinate 0.031
UQ + H+ + e- → UQH ⋅ 0.030
Cytochrome b5( Fe3+)+ e - → cytochrome b5(Fe2+) 0.020
[FAD]+2 H++2 e- → [FADH2] 0.003-0.091*
Cytochrome bL( Fe3+)+ e - → cytochrome bL(Fe2+) -0.100
Oxaloacetate + 2 H+ + 2 e- → malate -0.166
Pyruvate + 2 H+ + 2 e- → lactate -0.185

44. FAD + 2 H+ + 2 e- → FADH2 -0.219
NAD+ + 2 H+ + 2 e- → NADH + H+ -0.320
NADP+ + 2 H+ + 2 e- → NADPH + H+ -0.320

50. Figure 21.29 · The structures of several inhibitors of electron transport and

52. F

53. F

56. OBRIGADA !!!