3.1 Enzymes

Enzymes

proteins that catalyze(speed up) reactions by lowering the activation energy(the initial input of energy to start a reaction)

not consumed by a reaction

they do this by bringing reacting molecules close together in the correct position, enzyme active sites can be charged which can alter the substrate to promote catalysis, or they can change the shape of the substrate 

some enzymes consist of only polypeptide chains, while others require cofactors

Enzyme-Substrate complex

enzymes act on substrates, and substrates bind to compatible active sites

Substrates

a specific reactant that an enzyme acts upon to catalyze a biochemical reaction

Active site

area for substrate to bind

enzymes can only mediate a reaction if the substrate is compatible(the shape and charge) with the active site

when a substrate binds to the active site, both the enzyme and the substrate will change shape slightly, which helps to position the substrate so bonds can be broken/formed easier

Enzyme function

enzymes break down complex molecules and also build complex molecules

Cofactors

non protein molecules that bind to enzymes and assist enzyme function

some are metallic ions(iron, copper, zinc, etc)

others are small organic compounds called coenzymes, which assist enzymes in catalysis and act as electron carriers during reactions