The Enzyme Commission number (EC number) is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze.[1] As a system of enzyme nomenclature, every EC number is associated with a recommended name for the corresponding enzyme-catalyzed reaction.
EC numbers do not specify enzymes but enzyme-catalyzed reactions. If different enzymes (for instance from different organisms) catalyze the same reaction, then they receive the same EC number.[2] Furthermore, through convergent evolution, completely different protein folds can catalyze an identical reaction (these are sometimes called non-homologous isofunctional enzymes)[3] and therefore would be assigned the same EC number. By contrast, UniProt identifiers uniquely specify a protein by its amino acid sequence.[4]
Every enzyme code consists of the letters "EC" followed by four numbers separated by periods. Those numbers represent a progressively finer classification of the enzyme. Preliminary EC numbers exist and have an 'n' as part of the fourth (serial) digit (e.g. EC 3.5.1.n3).[2]
For example, the tripeptide aminopeptidases have the code "EC 3.4.11.4", whose components indicate the following groups of enzymes:
EC 3 enzymes are hydrolases enzymes (enzymes that use water to break up some other molecule)
Similarity between enzymatic reactions can be calculated by using bond changes, reaction centres or substructure metrics (formerly EC-BLAST], now the EMBL-EBI Enzyme Portal).[6]
Historyedit
Before the development of the EC number system, enzymes were named in an arbitrary fashion, and names like old yellow enzyme and malic enzyme that give little or no clue as to what reaction was catalyzed were in common use. Most of these names have fallen into disuse, though a few, especially proteolyic enzymes with very low specificity, such as pepsin and papain, are still used, as rational classification on the basis of specificity has been very difficult.
By the 1950s the chaos was becoming intolerable, and after Hoffman-Ostenhof[7] and Dixon and Webb[8] had proposed somewhat similar schemes for classifying enzyme-catalyzed reactions, the International Congress of Biochemistry in Brussels set up the Commission on Enzymes under the chairmanship of Malcolm Dixon in 1955. The first version was published in 1961, and the Enzyme Commission was dissolved at that time, though its name lives on in the term EC Number. The current sixth edition, published by the International Union of Biochemistry and Molecular Biology in 1992 as the last version published as a printed book, contains 3196 different enzymes. Supplements 1-4 were published 1993–1999. Subsequent supplements have been published electronically, at the website of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology.[5] In August 2018, the IUBMB modified the system by adding the top-level EC 7 category containing translocases.[9]
TC number (classification of membrane transport proteins)
Referencesedit
^Webb, E. C. (1992). Enzyme nomenclature 1992: recommendations of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology on the nomenclature and classification of enzymes. Academic Press. ISBN978-0-12-227164-9.
^ ab"ENZYME (Enzyme nomenclature database)". ExPASy. from the original on 21 March 2019. Retrieved 24 April 2019.
^Omelchenko MV, Galperin MY, Wolf YI, Koonin EV (2010). "Non-homologous isofunctional enzymes: a systematic analysis of alternative solutions in enzyme evolution". Biology Direct. 5 (1): 31. doi:10.1186/1745-6150-5-31. PMC2876114. PMID 20433725.
^Apweiler R, Bairoch A, Wu CH, Barker WC, Boeckmann B, Ferro S, Gasteiger E, Huang H, Lopez R, Magrane M, Martin MJ, Natale DA, O'Donovan C, Redaschi N, Yeh LS (Jan 2004). "UniProt: the Universal Protein knowledgebase". Nucleic Acids Research. 32 (Database issue): D115–9. doi:10.1093/nar/gkh131. PMC308865. PMID 14681372.
^ abMoss GP. . International Union of Biochemistry and Molecular Biology on the Nomenclature and Classification of Enzymes by the Reactions they Catalyse. Archived from the original on 2018-09-10. Retrieved 2006-03-14.
^Rahman SA, Cuesta SM, Furnham N, Holliday GL, Thornton JM (Feb 2014). "EC-BLAST: a tool to automatically search and compare enzyme reactions". Nature Methods. 11 (2): 171–174. doi:10.1038/nmeth.2803. PMC4122987. PMID 24412978.
^Hoffman-Ostenhof, O (1953). "Suggestions for a more rational classification and nomenclature of enzymes". Advances in Enzymology and Related Areas of Molecular Biology. Vol. 14. pp. 219–260. doi:10.1002/9780470122594.ch7. ISBN9780470122594. PMID 13057718. {{cite book}}: |journal= ignored (help)
^Dixon, M; Webb, E.C. (1958). Enzymes. London: Longmans Green. pp. 183–227.
^Tipton, Keith (August 2018). "Enzyme Nomenclature News: Translocases (EC 7): A new EC Class". ExplorEnz: the primary source of the IUBMB enzyme list. from the original on 10 September 2018. Retrieved 3 November 2018.
Enzyme Nomenclature, authoritative website by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology, maintained by G.P. Moss
enzyme, commission, number, confused, with, european, community, number, number, numerical, classification, scheme, enzymes, based, chemical, reactions, they, catalyze, system, enzyme, nomenclature, every, number, associated, with, recommended, name, correspon. Not to be confused with European Community number The Enzyme Commission number EC number is a numerical classification scheme for enzymes based on the chemical reactions they catalyze 1 As a system of enzyme nomenclature every EC number is associated with a recommended name for the corresponding enzyme catalyzed reaction EC numbers do not specify enzymes but enzyme catalyzed reactions If different enzymes for instance from different organisms catalyze the same reaction then they receive the same EC number 2 Furthermore through convergent evolution completely different protein folds can catalyze an identical reaction these are sometimes called non homologous isofunctional enzymes 3 and therefore would be assigned the same EC number By contrast UniProt identifiers uniquely specify a protein by its amino acid sequence 4 Contents 1 Format of number 2 Top level codes 3 Reaction similarity 4 History 5 See also 6 References 7 External linksFormat of number editEvery enzyme code consists of the letters EC followed by four numbers separated by periods Those numbers represent a progressively finer classification of the enzyme Preliminary EC numbers exist and have an n as part of the fourth serial digit e g EC 3 5 1 n3 2 For example the tripeptide aminopeptidases have the code EC 3 4 11 4 whose components indicate the following groups of enzymes EC 3 enzymes are hydrolases enzymes enzymes that use water to break up some other molecule EC 3 4 are hydrolases that act on peptide bonds EC 3 4 11 are those hydrolases that cleave off the amino terminal amino acid from a polypeptide EC 3 4 11 4 are those that cleave off the amino terminal end from a tripeptideTop level codes editNB The enzyme classification number is different from the FORMAT NUMBER Top level EC numbers 5 Class Reaction catalyzed Typical reaction Enzyme example s with trivial nameEC 1Oxidoreductases Oxidation reduction reactions transfer of H and O atoms or electrons from one substance to another AH B A BH reduced A O AO oxidized Dehydrogenase oxidaseEC 2Transferases Transfer of a functional group from one substance to another The group may be methyl acyl amino or phosphate group AB C A BC Transaminase kinaseEC 3Hydrolases Formation of two products from a substrate by hydrolysis AB H2O AOH BH Lipase amylase peptidase phosphataseEC 4Lyases Non hydrolytic addition or removal of groups from substrates C C C N C O or C S bonds may be cleaved RCOCOOH RCOH CO2 or X A B Y A B X Y DecarboxylaseEC 5Isomerases Intramolecule rearrangement i e isomerization changes within a single molecule ABC BCA Isomerase mutaseEC 6Ligases Join together two molecules by synthesis of new C O C S C N or C C bonds with simultaneous breakdown of ATP X Y ATP XY ADP Pi SynthetaseEC 7Translocases Catalyse the movement of ions or molecules across membranes or their separation within membranes TransporterReaction similarity editSimilarity between enzymatic reactions can be calculated by using bond changes reaction centres or substructure metrics formerly EC BLAST now the EMBL EBI Enzyme Portal 6 History editBefore the development of the EC number system enzymes were named in an arbitrary fashion and names like old yellow enzyme and malic enzyme that give little or no clue as to what reaction was catalyzed were in common use Most of these names have fallen into disuse though a few especially proteolyic enzymes with very low specificity such as pepsin and papain are still used as rational classification on the basis of specificity has been very difficult By the 1950s the chaos was becoming intolerable and after Hoffman Ostenhof 7 and Dixon and Webb 8 had proposed somewhat similar schemes for classifying enzyme catalyzed reactions the International Congress of Biochemistry in Brussels set up the Commission on Enzymes under the chairmanship of Malcolm Dixon in 1955 The first version was published in 1961 and the Enzyme Commission was dissolved at that time though its name lives on in the term EC Number The current sixth edition published by the International Union of Biochemistry and Molecular Biology in 1992 as the last version published as a printed book contains 3196 different enzymes Supplements 1 4 were published 1993 1999 Subsequent supplements have been published electronically at the website of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology 5 In August 2018 the IUBMB modified the system by adding the top level EC 7 category containing translocases 9 See also editList of EC numbers List of enzymes TC number classification of membrane transport proteins References edit Webb E C 1992 Enzyme nomenclature 1992 recommendations of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology on the nomenclature and classification of enzymes Academic Press ISBN 978 0 12 227164 9 a b ENZYME Enzyme nomenclature database ExPASy Archived from the original on 21 March 2019 Retrieved 24 April 2019 Omelchenko MV Galperin MY Wolf YI Koonin EV 2010 Non homologous isofunctional enzymes a systematic analysis of alternative solutions in enzyme evolution Biology Direct 5 1 31 doi 10 1186 1745 6150 5 31 PMC 2876114 PMID 20433725 Apweiler R Bairoch A Wu CH Barker WC Boeckmann B Ferro S Gasteiger E Huang H Lopez R Magrane M Martin MJ Natale DA O Donovan C Redaschi N Yeh LS Jan 2004 UniProt the Universal Protein knowledgebase Nucleic Acids Research 32 Database issue D115 9 doi 10 1093 nar gkh131 PMC 308865 PMID 14681372 a b Moss GP Recommendations of the Nomenclature Committee International Union of Biochemistry and Molecular Biology on the Nomenclature and Classification of Enzymes by the Reactions they Catalyse Archived from the original on 2018 09 10 Retrieved 2006 03 14 Rahman SA Cuesta SM Furnham N Holliday GL Thornton JM Feb 2014 EC BLAST a tool to automatically search and compare enzyme reactions Nature Methods 11 2 171 174 doi 10 1038 nmeth 2803 PMC 4122987 PMID 24412978 Hoffman Ostenhof O 1953 Suggestions for a more rational classification and nomenclature of enzymes Advances in Enzymology and Related Areas of Molecular Biology Vol 14 pp 219 260 doi 10 1002 9780470122594 ch7 ISBN 9780470122594 PMID 13057718 a href Template Cite book html title Template Cite book cite book a journal ignored help Dixon M Webb E C 1958 Enzymes London Longmans Green pp 183 227 Tipton Keith August 2018 Enzyme Nomenclature News Translocases EC 7 A new EC Class ExplorEnz the primary source of the IUBMB enzyme list Archived from the original on 10 September 2018 Retrieved 3 November 2018 External links edit nbsp Wikidata has the property nbsp EC enzyme number P591 see uses Enzyme Nomenclature authoritative website by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology maintained by G P Moss Enzyme nomenclature database by ExPASy List of all EC numbers by BRENDA Browse PDB structures by EC number Browse SCOP domains by EC number by dcGO Compare EC numbers using EC Blast Archived 2019 05 30 at the Wayback Machine Portal nbsp Biology Retrieved from https en wikipedia org w index php title Enzyme Commission number amp oldid 1172023847, wikipedia, wiki, book, books, library,
