Fundamentals of Microbiology

3.3.3 Mechanism of Enzymatic Action

The general sequence of events in enzyme action is as follows

1. The surface of the substrate contacts a specific region of the surface of the enzyme molecule, called the active site.

2. A temporary intermediate compound forms, called an enzyme-substrate complex.

3. The substrate molecule is transformed by the re­arrangement of existing atoms, the breakdown of the substrate molecule, or combination with another sub­strate molecule.

4. The transformed substrate molecules-the products of the reaction-are released from the enzyme mole­cule because they no longer fit in the active site of the enzyme.

5. The unchanged enzyme is now free to react with other substrate molecules.

As a result of these events, an enzyme speeds up a chemi­cal reaction.