Enzymes and Metabolism

1) Enzymes are proteins which catalyze reactions in cells. Since they are proteins they are made from amino acids.

2) They are called catalysts because they are unchanged and can be re-used over and over.

3) Enzymes reduce the activation energy required to make a reaction happen.

4) Substrates bind to the active site of an enzyme and convert the substrates into products

Figure Describing Enzymes

5) The three dimensional shape of the enzyme and of the active site determines its activity.

6) The way in which a substrate fits into an active site is often referred to as the lock and key model.

7) The active site of an enzyme may also change shape slightly to fit a substrate. This is referred to as induced fit.

8) Some enzymes also require cofactors (such as iron, copper or zinc), coenzymes (such as biotin, coenzyme A or ATP) and prosthetic groups (such as heme or flavin).

9) Enzymes can be inhibited by binding to certain compounds. Competitive inhibitors bind to the active site of the enzyme non-competitive inhibitors bind to a part of the enzyme other than the active site.

10) Enzymes can lose their shape (become denatured) and become inactive due to temperature or pH changes.