Substrate level phosphorylation is catalysed by
**Core Concept**
Substrate-level phosphorylation is a type of energy coupling mechanism in cellular respiration, where a high-energy phosphate group is directly transferred from a high-energy intermediate to ADP, generating ATP. This process occurs in conjunction with the transfer of electrons during the citric acid cycle and fatty acid oxidation.
**Why the Correct Answer is Right**
Substrate-level phosphorylation is catalyzed by specific enzymes, such as pyruvate kinase in glycolysis, phosphoglycerate kinase in glycolysis, and succinyl-CoA synthetase in the citric acid cycle. These enzymes facilitate the direct transfer of high-energy phosphate groups to ADP, resulting in the production of ATP. The correct answer is a specific enzyme involved in substrate-level phosphorylation.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specifically relate to substrate-level phosphorylation.
**Option B:** This option is incorrect because it refers to oxidative phosphorylation, a different type of energy coupling mechanism.
**Option C:** This option is incorrect because it is a type of enzyme involved in oxidative phosphorylation, not substrate-level phosphorylation.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that substrate-level phosphorylation occurs in conjunction with the transfer of electrons during cellular respiration, resulting in the production of ATP. This process is distinct from oxidative phosphorylation, which relies on the electron transport chain.
**Correct Answer:** C. Succinyl-CoA synthetase.