What is "cofactor"

n. 1 a contributing factor 2 (context biochemistry English) a substance, especially a coenzyme or a metal, that must be present for an enzyme to function 3 (context biochemistry English) a molecule that binds to and regulates the activity of a protein 4 (context mathematics English) the result of a number being divided by one of its factors

n. a substance (as a coenzyme) that must join with another to produce a given result

Cofactor may refer to:

• A domain parameter in Elliptic curve cryptography, defined as the (linear algebra)]], the signed minor of a matrix
• Minor (linear algebra), an alternative name for the determinant of a smaller matrix than that which it describes
• Cofactor (biochemistry), a substance that needs to be present in addition to an enzyme for a certain reaction to be catalysed
• Shannon cofactor, a term in Boole's (or Shannon's) expansion of a Boolean function

A cofactor is a non- protein chemical compound or metallic ion that is required for a protein's biological activity to happen. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations.

Cofactors can be subdivided into either one or more inorganic ions, or a complex organic or metalloorganic molecule called a coenzyme; most of which are derived from vitamins and from required organic nutrients in small amounts. A cofactor that is tightly or even covalently bound is termed a prosthetic group. Additionally, some sources also limit the use of the term "cofactor" to inorganic substances. An inactive enzyme without the cofactor is called an apoenzyme, while the complete enzyme with cofactor is called a holoenzyme.

Some enzymes or enzyme complexes require several cofactors. For example, the multienzyme complex pyruvate dehydrogenase at the junction of glycolysis and the citric acid cycle requires five organic cofactors and one metal ion: loosely bound thiamine pyrophosphate (TPP), covalently bound lipoamide and flavin adenine dinucleotide (FAD), and the cosubstrates nicotinamide adenine dinucleotide (NAD) and coenzyme A (CoA), and a metal ion (Mg).

Organic cofactors are often vitamins or are made from vitamins. Many contain the nucleotide adenosine monophosphate (AMP) as part of their structures, such as ATP, coenzyme A, FAD, and NAD. This common structure may reflect a common evolutionary origin as part of ribozymes in an ancient RNA world. It has been suggested that the AMP part of the molecule can be considered to be a kind of "handle" by which the enzyme can "grasp" the coenzyme to switch it between different catalytic centers.