- Prosthetic group
A prosthetic group is a non-protein (non-
amino acid ) component of aconjugated protein that is important in the protein's biological activity. [cite web |url=http://www.chem.qmul.ac.uk/iupac/bioinorg/PR.html#24 |title=Glossary of Terms Used in Bioinorganic Chemistry: Prosthetic groups |accessdate=2007-10-30 |last=de Bolster |first=M.W.G. |date=1997 |publisher=International Union of Pure and Applied Chemistry] The prosthetic group may be organic (such as avitamin ,sugar , orlipid ) orinorganic (such as ametal ion). Prosthetic groups are bound tightly to proteins and may even be attached through acovalent bond . They often play an important role in the function ofenzymes . A protein without its prosthetic group is called anapoprotein , while a protein combined with its prosthetic group is called aholoprotein .Prosthetic groups are a subset of cofactors and differ from
coenzyme s in that they bind permanently to the enzyme as opposed to temporarily for coenzymes. [cite web |url=http://www.chem.qmul.ac.uk/iupac/bioinorg/CD.html#34 |title=Glossary of Terms Used in Bioinorganic Chemistry: Cofactors |accessdate=2007-10-30 |last=de Bolster |first=M.W.G. |date=1997 |publisher=International Union of Pure and Applied Chemistry] In enzymes, prosthetic groups are involved in theactive site in some way.The
heme group inhemoglobin is a prosthetic group. Further examples of organic prosthetic groups are vitamin derivatives:thiamine (vitamin B1),thiamine pyrophosphate ,pyridoxal-phosphate andbiotin . Since prosthetic groups are often vitamins or made from vitamins, this is one of the reasons why vitamins are required in the human diet. Inorganic prosthetic groups are usuallytransition metal ions such asiron (inheme groups, for example incytochrome c oxidase andhemoglobin ),zinc (for example incarbonic anhydrase ),magnesium (for example in somekinase s), andmolybdenum (for example innitrate reductase ).List of prosthetic groups
References
ee also
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Cofactor (biochemistry) External links
* [http://www.bio.mtu.edu/%7Ehlyoungs/BL4010/cofactors.ppt Cofactors PowerPoint lecture]
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