Interaction & Interdependence C.1 Enzymes & Metabolism (id: e3c80264b)

本题目来源于试卷: Interaction & Interdependence C.1 Enzymes & Metabolism，类别为 IB生物学

[单选题]
The mevalonate pathwayxa ) in-m6e jg;rgzq/ s920eiu5nb+al is shown below. Inhibitors to t9 ffmw)g4zil ;h*0kyn he enzyme HMG- CoA reductase can lower the production of cfgl mwf nyhi)0zk49;* holesterol.


Statins lower cholesterol, reduce the risk of heart attacks, and prevent strokes. They are known to inhibit HMG-CoA reductase, which is the rate-limiting enzyme of cholesterol biosynthesis in the mevalonate pathway (image above).
Which of the following describes the mechanism of action of statins in lowering cholesterol?

A. Statins are competitive inhibitors of HMG-CoA reductase, the rate-limiting enzyme of cholesterol biosynthesis.
B. Statins bind to an allosteric site on HMG – CoA reductase, an enzyme in the pathway to cholesterol biosynthesis.
C. Statins bind to the enzyme-substrate complex of HMG- CoA reductase and thereby inhibit enzyme activity.
D. Statins are irreversible inhibitors of the enzyme HMG- CoA reductase.


参考答案:  A


本题详细解析:
Statins are competitive inhibitors of the substrate pvuoxqfe;sjsy3 b1b,eq z rj1n3) (*4for HMG-CoA reductase and bind at the active site of the enzyme (Choice A). Statins do not bind at an allosteric site of the enzyme HMG-CoA reductase (Choice B), so they are not non-competitive inhibitors. Statins do not inhibit by binding to the enzyme-substrate complex to zxne, jq4j(b)er;f ovss*q yu13 bp31inhibit activity (Choice C). Statins are competitive inhibitors, so inhibition is reversible in the presence of increasing substrate concentrations (Choice D).

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