Increase rate of reaction by lowering activation energy
Most are proteins
Specific – conversion of one specific substance to one product
May require cofactors or coenzymes
Carefully regulated
delta G = free energy
Free energy of the product minus the free energy of the reactants
delta G is negative for enzymatic reaction because energy is released (exergonic reaction)
delta Ea = activation energy
Energy barrier that must be overcome for a reaction to proceed
Enzymes lower activation energy of a reaction by stabilizing transition state
Energy required to get to equilibrium (rate of forward and reverse reactions are the same) correlates with ?G and is unchanged in the presence or absence of enzyme
Enzyme doesn't dictate whether reaction will proceed but determines speed of reaction
ENZYME ACTIVE SITE
3D structure produces active site
Shaped so that substrate fits in
Product of an enzymatic reaction has lower affinity for binding site: exits binding site and is released
COFACTORS AND COENZYMES
Bind cofactor binding site (distinct from active site)
Some enzymes inactive without cofactor or coenzyme
Many are vitamin-derived, metal ions, or other smaller organic molecules