Enzymes

Enzymes

• Enzymes are organic catalysts• A catalyst speeds up the rate of a reaction

• An enzyme will speed up a reaction by lower the activation energy of the reaction. This is the energy required for a chemical reaction to start

• Many enzymes are proteins, but not all. The way you know a compound is an enzyme is by looking at it’s name. All enzymes end in –ase.

• To speed up a reaction an enzyme will bind to a substrate. A substrate is the substance that is going to change or react

• Enzymes bind to substrates in special locations called active sites. Each enzymes active site is unique. Only one type of substrate will fit in the enzymes active site, like a lock and key.

• The enzyme and substrate together are called an enzyme-substrate complex and will remain together until the reaction is complete

• In a reaction enzymes• Do not change• Are not used up• Can be reused

In a solution, the enzymes will catalyze substrates continuously until all substrates are reacted. However, an enzyme can only react with one substrate at a time. If a solution has more substrate in it than a certain amount of enzyme can react to quickly, it is called a saturated solution.

• Coenzymes and cofactors are molecules that help the enzyme bind to the substrate. They are often vitamins

• Factors affecting enzyme activity• pH• temperature • substrate concentration• Each enzyme works best at an

optimum temperature and pH. Below or above the optimum range results in decreased enzyme activity

• Decreased activity is often the result of an enzyme becoming denatured, which is when an enzyme falls apart

• Inhibition: prevention of a reaction• Competitive inhibition: when a competitor molecule

binds in the same place as a substrate would and blocks the substrate from binding

• Non competitive inhibition: when a competitor molecule binds to the enzyme in a different place from where the substrate binds but causes a change in the enzyme so it can not bind to the substrate.

withenzymes

Without enzymes

Without enzymes

WITH ENZYME

ENZYME

SUBSTRATE

Active site

Enzyme-substrate complex