Substrate-level phosphorylation seen in reaction catalysed in:
**Core Concept**
Substrate-level phosphorylation is a type of phosphorylation reaction in which a high-energy phosphate group is transferred directly from a phosphate donor to ADP, generating ATP. This process occurs in specific enzymes, such as phosphorylase and kinases, which have a built-in phosphotransferase domain.
**Why the Correct Answer is Right**
Substrate-level phosphorylation is a key mechanism in glycolysis, where it occurs in the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate by the enzyme phosphoglycerate kinase (PGK). This reaction involves the direct transfer of a phosphate group from 1,3-bisphosphoglycerate to ADP, resulting in the production of ATP and 3-phosphoglycerate. This process is an essential step in glycolysis, as it generates a significant portion of the ATP produced during this metabolic pathway.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to substrate-level phosphorylation.
**Option B:** This option is incorrect as it refers to a different type of phosphorylation reaction.
**Option C:** This option is not correct as it does not describe a substrate-level phosphorylation reaction.
**Clinical Pearl / High-Yield Fact**
Substrate-level phosphorylation is a critical mechanism in glycolysis, producing a significant portion of the ATP generated during this metabolic pathway. It is essential to understand this process to appreciate the regulation of glycolysis and its role in cellular energy metabolism.
**Correct Answer:** C.