Enzymes

Enzymes (catalysts) - are proteins made of amino acids

What do they do? Help speed up a chemical reaction by lowering the energy needed to start the reaction- also known as the activation energy Activation energy – “start energy”

Enzymes are reusable: Enzymes are not changed during the reaction, they do the changing

an enzyme only acts on it’s perfect match, 1 specific substrate Enzymes are specific: an enzyme only acts on it’s perfect match, 1 specific substrate Puzzle pieces or lock and key ( key only opens one door/lock)

Substrate vs. Active Site Substrate: is what the enzyme acts on Active site: where substrate binds/ attaches to enzyme

How Do Enzymes Work? Action occurs at the enzymes active site Specific substrate attaches and then is either digested/ synthesized Enzyme substrate complex = when substrate and enzyme are together. E+ S  ES  E + P

There are two models of enzyme action: lock & key model  substrate & the enzyme fit together perfectly

There are two models of enzyme action: induced-fit model  enzymes change shape slightly to accommodate the substrate

Competitive Inhibitors

Factors affecting enzyme action Some factors can cause an enzyme to be denatured- enzyme shape changes and no longer works

Factors affecting enzyme action Temperature – enzymes work best at certain temperatures EX: 37oC is best for human enzymes in the body

Factors affecting enzyme action pH – enzymes work best at certain pH; ex.) Amylase in saliva at pH 7, Pepsin in the stomach at pH 2-3

Factors affecting enzyme action Substrate & enzyme concentrations –depends on how much of the substrate & enzyme is available.

Factors affecting enzyme action Coenzymes – helpers such as vitamins & minerals