substratespecific

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Ch. 6 Contents

General
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------------------Online--------------------------------wilcox@sunline.net Ch. 6 Metabolism of carbohydrates, fats, proteins, nucleic acids

7. Enzymes are Substrate Specific

Each enzyme has an active site. The active site is shaped to fit a specific substrate molecule. In the Figure below observe in Step 1 how sucrose fits perfectly in the active site. For sucrose to enter the active site, it must collide with the front of the molecules. If it collides with the back side, it will simply bounce off.

When the substrate enters the active site the enzyme actually changes shape allowing the enzyme to "embrace" the substrate. This embrace is called an "induced fit." This induced fit involves hydrogen bonding and transfers some energy from the enzyme to the substrate; think of it as a strong hand shake. This lowers the energy required for the reaction to proceed. Click here for an illustration.

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8. Enzyme Activity