In the glycolytic pathway, ATP is generated directly at the substrate level rather than through the electron transport chain. Which pair of enzymes catalyzes these substrate-level phosphorylation reactions?

• A Hexokinase and phosphofructokinase-1
• B Phosphoglucose isomerase and triose phosphate isomerase
• C Glyceraldehyde-3-phosphate dehydrogenase and enolase
• D Phosphoglycerate kinase and pyruvate kinase ✓

Explanation

Phosphoglycerate kinase transfers a phosphate from 1,3-bisphosphoglycerate to ADP forming ATP, and pyruvate kinase transfers a phosphate from phosphoenolpyruvate to ADP forming ATP. These are the two substrate-level phosphorylation steps of glycolysis. Hexokinase and PFK-1 consume ATP, while glyceraldehyde-3-phosphate dehydrogenase produces NADH and enolase merely dehydrates 2-phosphoglycerate without making ATP.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.