Which of the following biochemical reaction is associated with substrate level phosphorylation?: (A) Fumarate to malate, (B) Succinate to fumarate, (C) Succinyl CoA to Succinate, (D) Acetoacetate to a-ketoglutarate
Answer is C. Conversion of succinyl CoA to succinate is an example of substrate level phosphorylation in which a high energy phosphate is generated from the energy trapped in the thioester bond of succinyl CoA. Enzyme succinic thiokinase catalyses this step. In this reaction a molecule of GDP is phosphorylated into GTP and succinate is formed. GTP so formed is conveed into ATP by reacting with an ADP molecule. Ref: Lippincott's Biochemistry, 2nd Edition, Page 109; Textbook of Biochemistry By D M Vasudevan, 3rd Edition, Pages 75-77, 194, 204