Differentiate allosteric enzymes from Michaelis-Menten enzymes.

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Allosteric enzymes differ from Michaelis-Menten enzymes in how their activity and kinetics respond to substrate and regulators. Allosteric enzymes have multiple subunits and exhibit cooperative binding, so when substrate or an effector binds at one site, it changes the activity of other sites. This cooperative interaction produces a sigmoidal (S-shaped) rate versus substrate curve rather than a simple, single-peak hyperbola. They’re regulated by effectors that bind at allosteric sites (sites other than the active site), which can either enhance or inhibit activity by shifting the enzyme between different conformations (often described as tense and relaxed states).

Michaelis-Menten enzymes, on the other hand, typically show hyperbolic kinetics, consistent with non-cooperative binding at a single active site. Their activity is largely governed by substrate concentration, and regulation is usually through substrate availability or classic inhibitors/activators that do not operate through allosteric sites.

So, the key distinction is sigmoidal kinetics and regulation by allosteric effectors for allosteric enzymes, versus hyperbolic kinetics and regulation primarily by substrate concentration for Michaelis-Menten enzymes.