Question

In which of the following reaction substrate-level phosphorylation occurs during respiration?

• A. Citric acid $ \, \rightarrow \, \alpha $ -ketoglutaric acid
• B. Malic acid $ \rightarrow $ oxaloacetic acid
• C. $\alpha $ -ketoglutaric acid $ \rightarrow $ Succinyl-CoA
• D. Succinyl-CoA $ \rightarrow $ Succinic acid

Answer 1

Answer: (D)

Substrate-level phosphorylation is the direct synthesis of ATP in the reaction mechanism, also known as transphosphorylation. In Kreb's cycle during conversion of succinyl CoA to succinic acid a molecule of GTP is synthesized. In a coupled reaction GTP is converted to GDP with the simultaneous synthesis of ATP from ADP.