Enzymes: Enzymes are soluble protein molecules that can speed up chemical reactions in cells.
In living organisms, enzymes catalyze numerous biochemical reactions that sustain life and are involved in growth and reproductive functions.
Most enzymes are proteins, but some enzymes called ribozymes are made of RNA. Some DNA molecules, called deoxyribozymes, have been found to have catalytic activity. In addition, some antibodies, usually prepared artificially, have catalytic activity and are called abzymes.