Multiple Choice
In enzyme-catalyzed reactions, can a single enzyme molecule be reused to catalyze reactions with multiple substrate molecules over time?
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6. Enzymes and Enzyme Kinetics
Enzymes
Multiple Choice
In general, how many times can a single enzyme molecule be used to catalyze a reaction before it is consumed?
A
It can be used repeatedly for many catalytic cycles because it is not consumed by the reaction (until it is denatured or inhibited).
B
It can be used exactly twice because enzymes have two active sites that are used once each.
C
It can be used only once because it is converted into product during catalysis.
D
It can be used a fixed number of times equal to the reaction stoichiometric coefficient for the enzyme.
Verified step by step guidance1
Understand the role of an enzyme in a biochemical reaction: enzymes act as catalysts, which means they speed up reactions without being consumed or permanently altered in the process.
Recall that enzymes have an active site where substrate molecules bind and are converted into products, but the enzyme itself remains unchanged after the reaction.
Recognize that because the enzyme is not consumed, it can participate in multiple catalytic cycles, repeatedly binding substrates and converting them to products.
Note that the number of active sites on an enzyme does not limit the number of times it can catalyze a reaction; rather, it affects how many substrate molecules can be processed simultaneously.
Conclude that an enzyme can be used repeatedly many times until it is denatured (loses its structure) or inhibited, but it is not consumed or used up in the reaction itself.
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