positive modulation

biochemistry

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July 1, 2026

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In biochemistry, positive modulation refers to a regulatory mechanism where a molecule, known as an allosteric effector, is required for an enzyme to function efficiently. These enzymes exhibit minimal activity without the appropriate effector binding to a site distinct from the enzyme's active site. This binding alters the enzyme's shape, influencing its catalytic activity.12

A key example is the fixation of carbon dioxide onto pyruvate or phosphoenolpyruvate, which only occurs at a significant rate when acetyl coenzyme A is present. Acetyl coenzyme A acts as a positive allosteric effector in this process. This mechanism allows cells to finely tune metabolic pathways, ensuring that reactions proceed only when necessary and in response to the availability of other metabolites.12

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metabolism
Positive modulation
Not all pacemaker enzymes are controlled by inhibition of their activity. Instead, some are subject to positive modulation—i.e., the effector is required for the efficient functioning of the enzyme. Such enzymes exhibit little activity in the absence of the appropriate allosteric effector. One…
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Not all pacemaker enzymes are controlled by inhibition of their activity. Instead, some are subject to positive modulation—i.e., the effector is required for the efficient functioning of the enzyme. Such enzymes exhibit little activity in the absence of the appropriate allosteric effector. One…
Read More