Activities of Enzymes

There are five major mechanisms by which enzymes speed up the rate of metabolic reactions:

Functional-group transfers: one molecule gives up a functional group, and another molecule accepts it.
Electron transfer: one or more electrons are stripped from one molecule and donated to another molecule.
Rearrangement: a juggling of internal bonds converts one type of organic compound into another.
Condensation: through covalent bonding, two molecules combine to form a larger molecule.
Cleavage: a molecule splits into two smaller ones.

In condensation reactions, small molecules can combine to form larger ones.

In hydrolysis reactions, one larger molecule is split by the addition of hydrogen and hydroxyl ions (from water) into its components.