Chapter 7, Problem 18RE

Interpretation Introduction

Interpretation:

The possibility of envisioning a model for the behavior of allosteric enzymes, other than the ones that have already been proposed (the concerted model and the sequential model).

Concept introduction:

Allosteric enzymes bind to the effector molecule at sites other than the enzyme’s active site, and the binding of the effector changes the activity of the enzyme. An allosteric enzyme shows cooperativity, which can be positive or negative. Its behavior in terms of cooperativity is explained by two models, which are the concerted model and the sequential model.

An allosteric enzyme exists in two forms—T-form and R-form. The T-form is the inactive form and the R-form is the active form of the enzyme. The concerted model shows the equilibrium between the T- and R-forms. All subunits of an enzyme exist in either of the forms, and in the sequential model, the T-form changes into the R-form on the binding of the substrate.