Hydroxymethyltransferase

In biochemistry, this is the general name given to a class of enzymes: 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 → A + B–X

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

History

Some of the most important discoveries relating to transferases occurred in the early 1950s. Earliest discoveries of transferase activity occurred in other classifications of enzymes, including Beta-galactosidase, protease, and acid/base phosphatase. Prior to the realization that individual enzymes were capable of such a task, it was believed that two or more enzymes enacted functional group transfers.[1]

One such example of early transferase reclassification is the discovery and subsequent naming of uridyl transferase. In 1953, the enzyme uridine diphosphoglucose pyrophosphorylase (otherwise known as UDP-glucose pyrophosphorylase) was shown to be a transferase, when it was found that it could reversibly produce uridine triphosphate and glucose 1-phosphate from UDP-glucose and an organic pyrophosphate.[2]

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:

Transferase deficiencies

Transferase deficiencies are at the root of many common illnesses and diseases. The most common result of a transferase deficiency is a buildup of a cellular product. Succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency, for example leads to a buildup of ketones,[3] while carnitine palmitoyltransferase II deficiency leads to an excess long chain fatty acids, as the body lacks the ability to transport fatty acids into the mitochondria to be processed as a fuel source.[4] Galactosemia results from an inability to process galactose, a simple sugar.[5]

Transferase reactions

Transferases are involved in a myriad of reactions in the cell. Some examples of these reactions include CoA transferase, which transfers thiol esters[6] , N-acetyl transferase which is part of the pathway that metabolizes tryptophan[7] and in the regulation of pyruvate dehydrogenase also known as PDH[8] . The regulation of PDH involves both phosphatases, which remove phosphates, and kinases, which add phosphates

See also

  • Queen Mary, University of London



References