Enzyme Kinetics MCAT Practice Question
A clinician suspects a patient has a genetic mutation affecting the catalytic site of pyruvate dehydrogenase. In vitro kinetic studies reveal that Km remains unchanged at 0.5 mM compared to wild-type enzyme, but Vmax is reduced by 60%. Which of the following mechanisms best explains these kinetic findings?
Answer choices
- AThe mutation increases substrate binding affinity
- BThe mutation causes competitive inhibition of pyruvate binding
- CThe mutation prevents allosteric regulation by acetyl-CoA
- DThe mutation reduces the turnover number (kcat) of the enzymeCorrect answer
- EThe mutation increases the Michaelis constant through altered cofactor binding
- FThe mutation impairs the release of products from the enzyme-substrate complex
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