prosthetic group

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prosthetic group,

non-amino acid portions of certain proteinprotein,
any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight.
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 molecules. The key part of the prosthetic group may be either organic (such as a vitaminvitamin,
group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either the vitamins themselves are coenzymes, or they form integral parts of coenzymes.
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) or inorganic (such as a metal) and is usually required for biological activity, especially when the prosthetic group is complexed with an enzymeenzyme,
biological catalyst. The term enzyme comes from zymosis, the Greek word for fermentation, a process accomplished by yeast cells and long known to the brewing industry, which occupied the attention of many 19th-century chemists.
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The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Prosthetic Group


an organic and nonprotein compound that forms a part of conjugated proteins. In enzymatic catalysis the prosthetic group is usually referred to as a coenzyme. Coenzymes are firmly bonded to the protein part of a biocatalyst by an apoenzyme and remain affixed to the protein molecule for the duration of the catalysis; examples of coenzymes include lipoic acid, riboflavin, biotin, and hemes.

Carrier coenzymes differ from prosthetic groups. The activity of carrier coenzymes is associated with their transfer from one enzyme molecule to another. However, this differentiation is often arbitrary, since the same compound (for example, flavine-adenine dinucleotide) can sometimes act like a typical dissociating coenzyme, while at other times it remains firmly bonded to the protein.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

prosthetic group

[präs′thed·ik ′grüp]
A characteristic nonamino acid substance that is strongly bound to a protein and necessary for the protein portion of an enzyme to function; often used to describe the function, as in hemeprotein for hemoglobin.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.