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 diagram shows the pathway that c r83 94u vqckw ph8l ;6,c3hid8ksl ofgonverts threo .zf lka mv14(fu )(sbbx5lep 2nine to isoleucine.
What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?
A. Name is Competitive inhibition, Mechanism is Isoleucine binds to the active site on the enzyme.
B. Name is Competitive inhibition, Mechanism is Isoleucine binds to an allosteric site on the enzyme.
C. Name is End-product inhibition, Mechanism is Isoleucine binds to the active site on the enzyme.
D. Name is End-product inhibition, Mechanism is Isoleucine binds to an allosteric site on the enzyme.
参考答案: D
本题详细解析:
The diagram shows that threonine undergoes a serdxf+kjav l+j -:pq-7qies of enzyme-catalyzed reactions to produce isoleucine. At the end of this qql-fv+-jjkdxa: p 7 +pathway, if isoleucine accumulates it inhibits threonine dehydratase. So, the product of the pathway inhibits the conversion of threonine to isoleucine. This is an example of end-product inhibition. Isoleucine inhibits the enzyme in the pathway by binding to an allosteric site on the enzyme, not the active site. The binding of isoleucine changes the conformation of the enzyme such that the active site is no longer able to bind to threonine. Choice D is correct.
In competitive inhibition (Choices A and B), a substance binds to the active site on the enzyme to prevent the substrate from binding. In end-product inhibition, the product binds to the allosteric site, not the active site (Choice C).
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