cofactor
American Heritage Dictionary:
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co·fac·tor
(kō'făk'tər) 
n.
n.
- One of two or more contributing factors.
- A substance, such as a metallic ion or coenzyme, that must be associated with an enzyme for the enzyme to function.
Oxford Dictionary of Chemistry:
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cofactor
A nonprotein component essential for the normal catalytic activity of an enzyme. Cofactors may be organic molecules (coenzymes) or inorganic ions. They may activate the enzyme by altering its shape or they may actually participate in the chemical reaction.
Britannica Concise Encyclopedia:
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cofactor
An atom, organic molecule, or molecular group that is necessary for the catalytic activity ( catalysis) of many enzymes. A cofactor may be tightly bound to the protein portion of an enzyme and thus be an integral part of its functional structure, or it may be only loosely associated and free to diffuse away from the enzyme. Cofactors of the integral kind include metal atomssuch as iron, copper, or magnesiumor moderately sized organic molecules called prosthetic groups; many of the latter contain a metal atom, often in a coordination complex ( transition element). Removal of the cofactor from the enzyme's structure causes loss of its catalytic activity. Loosely associated cofactors are called coenzymes; examples include most members of the vitamin B complex. Rather than directly contributing to the catalytic ability of an enzyme, coenzymes participate with the enzyme in the catalytic reaction. Sometimes this distinction in definition is no longer made, and coenzyme is used in the broader sense of cofactor.
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A non-protein substance that is essential for the efficient functioning of an enzyme, binding with it during a reaction. Tightly bound cofactors are called prosthetic groups. ATP and NAD are cofactors.
Oxford Dictionary of Biochemistry:
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cofactor
- any accessory, nonprotein substance, commonly of low molecular mass, that is necessary for the activity of an enzyme. Metal-ion cofactors have been called activators; organic cofactors that are easily removable from the enzyme (e.g. by dialysis) may be called coenzymes, but if they are tightly bound they are often termed prosthetic groups. See also apoenzyme, holoenzyme.
- any amino acid that must be present in the medium to allow certain phages to be adsorbed by host bacteria.
| coenzyme factor, coenzyme R, coenzyme Q | |
| cofilin, cognitive neuroscience, coherent |
Saunders Veterinary Dictionary:
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cofactor
An element or principle, e.g. a coenzyme, with which another must unite in order to function.
- ristocetin c. — see ristocetin cofactor.
Random House Word Menu:
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categories related to 'cofactor'
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Cofactor
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Look up cofactor in Wiktionary, the free dictionary. |
Cofactor may refer to any of the following:
- Cofactor (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 expansion or Shannon cofactor, a derived function of another function, a notion useful in computer science and mathematics
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American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
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Oxford Dictionary of Chemistry
A Dictionary of Chemistry. Sixth Edition. Copyright © Market House Books Ltd, 2008. All rights reserved.
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Britannica Concise Encyclopedia
Britannica Concise Encyclopedia. © 1994-2012 Encyclopædia Britannica, Inc. All rights reserved. Read more
Oxford Dictionary of Sports Science & Medicine
The Oxford Dictionary of Sports Science & Medicine. Copyright © Michael Kent 1998, 2006, 2007. All rights reserved.
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Oxford Dictionary of Biochemistry
Oxford University Press. Oxford Dictionary of Biochemistry and Molecular Biology © 1997, 2000, 2006 All rights reserved.
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Saunders Veterinary Dictionary
Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.
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