Cofactor

Part of speech: noun

Definitions

1. A non-protein chemical compound that helps enzymes carry out reactions ; a number used in mathematics to adjust values in matrix determinants
2. A molecule or ion that binds to an enzyme and is essential for its functioning ; an auxiliary value applied in algebraic calculations involving matrices
3. An agent that assists enzymes by increasing their catalytic activity ; a scalar used in mathematical processes to simplify matrix computations

Etymology: "Cofactor" is a plain compound: the prefix "co-", meaning "together with" or "joint", attached to "factor". The "factor" half is the more interesting one. It descends from Latin "factor", a maker or doer, built on "facere", "to do or make", and it passed into English through Middle French "facteur" and Anglo-Norman "factour", reaching Middle English as "factour" before the modern spelling settled. In English it first meant an agent or commercial representative, someone who acts on another's behalf, and the sense of a contributing element in a result came later. The "co-" prefix is the same Latin "com-" (shortened to "co-" before some sounds) that gives English "cooperate" and "coexist". A cofactor, then, is something that works alongside another agent. In biochemistry it names a non-protein helper molecule, often a metal ion or a vitamin-derived compound, that an enzyme needs in order to perform its reaction. The enzyme does the catalysing, but the cofactor supplies a chemical ingredient the protein cannot provide on its own.

Synonyms: factor, component