Animation 8.2: Allosteric Regulation of Enzymes

INTRODUCTION

Cells tightly regulate their enzymatic reactions, allowing necessary reactions to proceed while inhibiting unnecessary or damaging ones. One means of regulating enzyme action is allosteric regulation, in which a molecule binds to an enzyme at a site other than the active site and changes the enzyme's activity. Such a molecule is an allosteric regulator. Some allosteric regulators activate enzymes, while others inhibit them.

CONCLUSION

Enzymes speed up chemical reactions, making reactions occur at the right time and place in a cell. Although enzymes are essential for life, they must be tightly regulated so that cells focus their energy and resources on appropriate cellular reactions. In this tutorial, we examine a means of regulating enzyme activity—allosteric regulation—in which regulators bind to the enzyme at a site different from the active site. Allosteric regulators are either inhibitors or activators. The binding of the regulator affects the activity of the enzyme.

Cells also use other means of regulating enzymes. For example, a cell may regulate the expression of a gene that codes for a particular enzyme. Also, a cell may modify an enzyme's activity by covalently attaching molecules, such as phosphate groups, to them. Cells use these and other regulation mechanisms to keep metabolic reactions in check.

Textbook Reference: Key Concept 8.5 Enzyme Activities Can Be Regulated