Citric Acid Cycle Flashcards
1
Q
Functions of the citric acid cycle
A
- Convert fuels to a common mobile fuel (NADH)
- Final meeting place for nearly all oxidizable substrates
- Provides intermediates for biosynthesis
2
Q
Pyruvate Dehydrogenase Complex
A
- Oxidizes Pyruvate to Acetyl CoA
- Located in matrix
- Consists of pyruvate dehydrogenase, dihydrolipoyl transacetylase, and dihydrolipoyl dehydrogenase
- E4 and E5 are regulatory enzymes
- TLCFN enzyme
3
Q
Pyruvate dehydrogenase
A
- E1 in pyruvate dehydrogenase complex
- Condensation/decarboxylation
- Prosthetic group: TPP (has thiamine=Vitamin B1)
4
Q
Dihydrolipoyl transferase
A
- E2 of pyruvate dehydrogenase complex
- Oxidative transfer, transacetylation
- Prosthetic groups: Lipoamide (serves as a swinging arm that makes kinetics faster)
5
Q
Dihydrolipoyl dehydrogenase
A
- E3 of pyruvate dehydrogenase complex
- Dehydrogenation
- Prosthetic group: FAD
6
Q
At what site does arsenite poisoning occur?
A
- Dihydrolipoamide involved in pyruvate dehydrogenase complex
- Binds to SH groups which is irreversible
7
Q
Citrate synthetase
A
- Condensation and hydrolysis
- Converts Acetyl CoA and Oxaloacetate to Citrate and CoA
8
Q
Aconitase
A
- Dehydration and hydration
- Converts citrate to isocitrate
- Facilitated by an iron sulfur center
9
Q
Isocitrate dehydrogenase
A
- Oxidative decarboxylation
- Converts isocitrate to α-Ketoglutarate
10
Q
α-Ketoglutarate dehydrogenase complex
A
- Oxidative decarboxylation and formation of thioester
- Converts α-ketoglutarate to succinyl coA, forms CO2
- TLCFN enzyme
11
Q
Succinyl CoA Synthetase
A
- Thioester cleavage coupled to GTP synthesis
- Succinyl coA to succinate
- Substrate level phosphorylation
- Common intermediate principle
12
Q
Succinate dehydrogenase
A
- Oxidation
- Transfers electrons to an FAD
- Succinate to fumarate
13
Q
Fumarase
A
- Hydration
- Fumarate to malate
14
Q
Malate dehydrogenase
A
- Oxidation
- Malate to oxaloacetate
- Malate can also exit the cell and serve as substrate for gluconeogenesis
