ENZYME

Enzyme Mechanism

Enzymes do two important things: • they recognize very specific substrates, • they perform specific chemical reactions

on them at fantastic speeds.

ACTIVE SITEThe active site is a specialized region of the

protein where the enzyme interacts with the substrate

TRANSITION STATEThe transition state is the highest-energy arrangement of atoms during a chemical

reaction.

CATALYSISThe reaction happens at a faster rate. The

catalyst is regenerted

LOCK AND KEYSpecificity model—the correct substrate fits into

the active site of the enzyme like a key into a lock. Only the right ke fits

INDUCED FIT

The binding of the correct substrate triggers a change in the structure of the enzyme that brings catalytic groups into exactly the right position to facilitate the

reaction

NONPRODUCTIVE BINDING

Poor substrates bind to the enzyme in a large number of different ways, only one of which is

correct. Good substrates bind only in the proper way.

ENZYME KINETICS

• The concentrations of substrate and product are invariably in molar units (M; this includes mM, M, etc.), but

• enzyme concentrations may be given in molar (M), milligrams per milliliter (mg/mL), or units/mL.

• The amount of enzyme you have can be expressed in molecules, milligrams, nanomoles (nmol), or units. A unit of enzyme is the amount of enzyme that will catalyze the formation of 1 mol of product per minute under specifically defined conditions.

• A unit is an amount, not a concentration.

COMPETITIVE INHIBITION

UNCOMPETITIVE INHIBITION

NONCOMPETITIVE INHIBITION