What does lactate dehydrogenase (LD) catalyze?

What does lactate dehydrogenase (LD) catalyze?

• A. The conversion of lactic acid to pyruvic acid
• B. The breakdown of triglycerides
• C. The conversion of glucose to ATP
• D. The hydrolysis of starch

Answer: (A)

Lactate dehydrogenase (LD) plays a critical role in the conversion of lactic acid to pyruvic acid. This enzyme facilitates the reversible reaction that interconverts lactic acid (or lactate) and pyruvate, which is a key step in glycolysis and is particularly important during anaerobic metabolism when oxygen levels are low. The presence of lactate and pyruvate is crucial for maintaining energy production under these conditions, as the conversion helps regenerate NAD+, which is necessary for glycolysis to continue.

In contrast, the processes related to the other options do not involve lactate dehydrogenase. The breakdown of triglycerides is catalyzed by lipases, the conversion of glucose to ATP involves multiple pathways including glycolysis and the citric acid cycle, and the hydrolysis of starch is facilitated by amylases. Each of these functions is distinct and does not relate to the activity of lactate dehydrogenase.