Answer:
1.(a ) alpha-ketoglutarate dehydrogenase
(c) malate dehydrogenase
(d) isocitrate dehydrogenase
2. b. isocitrate dehydrogenase d. alpha-ketoglutarate dehydrogenase
3. b. citrate synthase (c) succinyl-CoA synthesase
4. b. alpha-ketoglutarate dehydrogenase c. citrate synthase d. malate dehydrogenase
5. a. aconitase
Explanation:
The citric acid cycle is responsible for the oxidation of acetyl-CoA produced from pyruvate from glycolysis. The citric acid cycle has eight steps requiring nine enzymatic reactions involving eight enzymes.
The enzymes in the citric acid cycle are: citrate synthase
, aconitase, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase
, succinyl-CoA synthesase, succinate dehydrogenase
, fumarase
, and malate dehydrogenase
.
1. The dehydrogenation reactions of isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase
, and malate dehydrogenase produces NADH from isocitrate, alpha-ketoglutarate and malate respectively.
2. Oxidative decorboxylation (removal of carbon as CO₂) also occurs in the reactions of isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase to produce alpha-ketoglutarate and succinyl-CoA respectively.
3. Coenzyme-A (CoA-SH) is produced in the reactions of citrate synthase and succinyl-CoA sythetase to produce citrate and succinate respectively.
4. The enzymes alpha-ketoglutarate dehydrogenase has alpha-ketoglutarate as substrate
, whereas citrate synthase and malate dehydrogenase has oxaloacetate as substrate. These substrates are alpha-keto acids.
5. Aconitase catalyzes the conversion of citrate to isocitrate by first a dehydration and then a hydration reaction.
