BIOCHEMISTRY
ENZYMES AND METABOLISM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Succinate dehydrogenase is the enzyme, and fumarate is the substrate
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Succinate dehydrogenase is the enzyme, and malonic acid is the substrate.
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Succinate is the substrate, and fumarate is the product
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Fumarate is the product, and malonic acid is a noncompetitive inhibitor.
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Detailed explanation-1: -Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid.
Detailed explanation-2: -Presumably the dissociation of the enzyme-substrate complex takes place when succinic acid has been dehydrogenated to fumaric acid, but since malonic acid cannot be dehydrogenated, it does not readily dissociate from the enzyme, and consequently prevents it from reacting with succinic acid.
Detailed explanation-3: -Succinate dehydrogenase is also known as mitochondrial complex II, and inhibition of succinate dehydrogenase by dimethyl malonate has been reported to suppress the production of pro-inflammatory cytokines.
Detailed explanation-4: -The succinate dehydrogenase catalyses the oxidation of succinate into fumarate in the Krebs cycle (1), derived electrons being fed to the respiratory chain complex III to reduce oxygen and form water (2).