Prosthetic group

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A prosthetic group is a non-protein (non-amino acid) component of a conjugated protein that is important in the protein's biological activity.[1] The prosthetic group may be organic (such as a vitamin, sugar, or lipid) or inorganic (such as a metal ion). Prosthetic groups are bound tightly to proteins and may even be attached through a covalent bond. They often play an important role in the function of enzymes. A protein without its prosthetic group is called an apoprotein, while a protein combined with its prosthetic group is called a holoprotein.

Prosthetic groups are a subset of cofactors and differ from coenzymes in that they bind permanently to the enzyme as opposed to temporarily for coenzymes.[2] In enzymes, prosthetic groups are involved in the active site in some way.

The heme group in hemoglobin is a prosthetic group. Further examples of organic prosthetic groups are vitamin derivatives: thiamine (vitamin B1), thiamine pyrophosphate, pyridoxal-phosphate and biotin. 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 usually transition metal ions such as iron (in heme groups, for example in cytochrome c oxidase and hemoglobin), zinc (for example in carbonic anhydrase), magnesium (for example in some kinases), and molybdenum (for example in nitrate reductase).

Contents

[edit] List of prosthetic groups

Prosthetic group Function Distribution
Flavin mononucleotide [3] Redox reactions Bacteria, archaea and eukaryotes
Flavin adenine dinucleotide [3] Redox reactions Bacteria, archaea and eukaryotes
Pyrroloquinoline quinone [4] Redox reactions Bacteria
Pyridoxal phosphate [5] Transamination, decarboxylation and deamination Bacteria, archaea and eukaryotes
Biotin [6] Carboxylation Bacteria, archaea and eukaryotes
Methylcobalamin [7] Methylation and isomerisation Bacteria, archaea and eukaryotes
Thiamine pyrophosphate [8] Decarboxylation Bacteria, archaea and eukaryotes
Heme [9] Oxygen binding and redox reactions Bacteria, archaea and eukaryotes
Molybdopterin [10][11] Oxygenation reactions Bacteria, archaea and eukaryotes
Lipoic acid [12] Redox reactions Bacteria, archaea and eukaryotes

[edit] References

  1. ^ de Bolster, M.W.G. (1997). Glossary of Terms Used in Bioinorganic Chemistry: Prosthetic groups. International Union of Pure and Applied Chemistry. Retrieved on 2007-10-30.
  2. ^ de Bolster, M.W.G. (1997). Glossary of Terms Used in Bioinorganic Chemistry: Cofactors. International Union of Pure and Applied Chemistry. Retrieved on 2007-10-30.
  3. ^ a b Joosten V, van Berkel WJ (2007). "Flavoenzymes". Curr Opin Chem Biol 11 (2): 195–202. doi:10.1016/j.cbpa.2007.01.010. PMID 17275397. 
  4. ^ Salisbury SA, Forrest HS, Cruse WB, Kennard O (1979). "A novel coenzyme from bacterial primary alcohol dehydrogenases.". Nature 280 (5725): 843-4. doi:10.1038/280843a0.  PMID 471057
  5. ^ Eliot AC, Kirsch JF (2004). "Pyridoxal phosphate enzymes: mechanistic, structural, and evolutionary considerations". Annu. Rev. Biochem. 73: 383–415. doi:10.1146/annurev.biochem.73.011303.074021. PMID 15189147. 
  6. ^ Jitrapakdee S, Wallace JC (2003). "The biotin enzyme family: conserved structural motifs and domain rearrangements". Curr. Protein Pept. Sci. 4 (3): 217–29. doi:10.2174/1389203033487199. PMID 12769720. 
  7. ^ Banerjee R, Ragsdale SW (2003). "The many faces of vitamin B12: catalysis by cobalamin-dependent enzymes". Annu. Rev. Biochem. 72: 209–47. doi:10.1146/annurev.biochem.72.121801.161828. PMID 14527323. 
  8. ^ Frank RA, Leeper FJ, Luisi BF (2007). "Structure, mechanism and catalytic duality of thiamine-dependent enzymes". Cell. Mol. Life Sci. 64 (7-8): 892–905. doi:10.1007/s00018-007-6423-5. PMID 17429582. 
  9. ^ Wijayanti N, Katz N, Immenschuh S (2004). "Biology of heme in health and disease". Curr. Med. Chem. 11 (8): 981–6. doi:10.2174/0929867043455521. PMID 15078160. 
  10. ^ Mendel RR, Hänsch R (2002). "Molybdoenzymes and molybdenum cofactor in plants". J. Exp. Bot. 53 (375): 1689–98. doi:10.1093/jxb/erf038. PMID 12147719. 
  11. ^ Mendel RR, Bittner F (2006). "Cell biology of molybdenum". Biochim. Biophys. Acta 1763 (7): 621–35. PMID 16784786. 
  12. ^ Bustamante J, Lodge JK, Marcocci L, Tritschler HJ, Packer L, Rihn BH (1998). "Alpha-lipoic acid in liver metabolism and disease". Free Radic. Biol. Med. 24 (6): 1023–39. doi:10.1016/S0891-5849(97)00371-7. PMID 9607614. 

[edit] See also

[edit] External links

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Types of enzyme cofactors
Coenzymes
Prosthetic groups:
Organic group
Prosthetic groups:
Metals