V-type enzymes are named for their often remarkable changes in Vmax when they are allosterically activated. However, these enzymes also generally have a comparable change in their affinity for the substrate. When such enzymes are in a normal metabolic pathway, changes in the maximum activity can be up to 30-fold. To be included in this category, enzymes must have at least a doubling in Vmax, so that this allosteric effect can be physiologically or experimentally meaningful. When these enzyme activities are part of a regulatory switch, the change in activity may exceed 100,000-fold.
KeywordsPyruvate Carboxylase Regulatory Switch Saturate Substrate Allosteric Effect Phosphoglycerate Dehydrogenase
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