Enzymes

Enzymes

Enzyme • An organic catalyst

• Modifies and increases the rate of reaction • Can be reused but are eventually destroyed

• Large proteins with one or more polypeptide chains • Ends with –ase • Named after the substrate that they are acting upon • Acting on protein  protease • Acting on lipid  lipase

Protein nature • Enzymes are exclusively proteins or are proteins with non protein parts called coenzymes. • Coenzymes are often vitamins

Active site and Substrate • Active site : part of enzyme involved in reaction • Substrate: Chemical enzyme is acting upon

Enzyme Substrate Complex • Stage 1 • Enzyme forms temporary association with substrates

• Stage 2 • Brings substrates close physically and reaction occurs

• Stage 3 • Molecules separate

Lock and Key • Enzymes can only work on specific substances. • Explained as lock and key, only certain substrate can fit into certain enzyme

Rate of Reaction • Temperature • As temperature increase so does enzyme action to a point • To high a temperature and the enzyme structure changes and becomes ineffective. This is called enzy me denatura tio n • In the body this occurs at 40o C

Rate of reaction • Relative amounts of enzyme and substrate • Changing amount of substrate will not affect rate • More enzymes will always speed up reaction up to a point

• pH

• Different pH’s affect different enzymes differently