Transferases

In biochemistry, a transferase is an enzyme that catalyzes the transfer of a functional group (e.g. a methyl or phosphate group) from one molecule (called the donor) to another (called the acceptor). For example, an enzyme that catalyzed this reaction would be a transferase:


 * A–X + B &rarr; A + B–X

In this example, A would be the donor, and B would be the acceptor. The donor is often a coenzyme.

Nomenclature
Proper names of transferases are formed as "donor:acceptor grouptransferase." However, other names are much more common. The common names of transferases are often formed as "acceptor grouptransferase" or "donor grouptransferase." For example, a DNA methyltransferase is a transferase that catalyzes the transfer of a methyl group to a DNA acceptor.

Classification
Transferases are classified as EC 2 in the EC number classification. Transferases can be further classified into nine subclasses:
 * EC 2.1 includes enzymes that transfer one-carbon groups (methyltransferase)
 * EC 2.2 includes enzymes that transfer aldehyde or ketone groups
 * EC 2.3 includes acyltransferases
 * EC 2.4 includes glycosyltransferases
 * EC 2.5 includes enzymes that transfer alkyl or aryl groups, other than methyl groups
 * EC 2.6 includes enzymes that transfer nitrogenous groups (transaminase)
 * EC 2.7 includes enzymes that transfer phosphorus-containing groups (phosphotransferase, including polymerase and kinase)
 * EC 2.8 includes enzymes that transfer sulfur-containing groups (sulfurtransferase and sulfotransferase)
 * EC 2.9 includes enzymes that transfer selenium-containing groups