Enzymes

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Enzymes

Active sites.

All enzymes have active sites. Each enzyme has an active site that exactly fits its substrate. This means that each enzyme can only act on a particular kind of substrate.

The enzyme can be thought of as a 'lock', and the substrate as a 'key'. Only the correctly shaped key will fit into the lock.

All enzymes have certain properties.

All enzymes are proteins.

Enzymes are made inactive by high temperature: This is because all enzymes are protein molecules, which are damaged by heat.

Enzymes work best at a particular temperature: Enzymes which are found in the human body usually work best at about 37 'degrees celsius'.

Enzymes work best at a particular pH: pH is a measure of how acid or alkaline a solution is. Some enzymes work best in acid conditions (low pH). Others work best in alkaline solutions (high pH).

Enzymes are catalysts: They are not changed in the chemical reactions which they control. They can be used over and over again, so a small amount of enzyme can change a lot of substrate into a lot of product.

Enzymes are specific: This means that each kind of enzyme will only catalyse one kind of chemical reaction.

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