Substrate level phosphorylation is seen in reaction catalyzed by which enzyme of citric acid cycle?: (A) Pyruvate kinase, (B) Succinate thiokinase, (C) Phosphoglycerate kinase, (D) All of the above
Answer is B. The reaction involves a substrate level phosphorylation whereby a high energy phosphate is generated from the energy trapped in the thioester bond of succinyl CoA. The enzyme is succinate thiokinase (step 5, Fig.18.2). A molecule of GDP is phosphorylated to GTP and succinate is formed. The GTP can be conveed to ATP by reacting with an ADP molecule: GTP + ADP - GDP + ATPRef: DM Vasudevan, Page no: 218