Restriction enzymes nomenclature

Enzyme modification, performance improvement, 3 671 Enzyme multiplied immunological technique (EMIT), 12 97 Enzyme Nomenclature, 17 402 Enzyme-product (EP) complex, 10 318 Enzyme production, Bacillus and, 12 477 Enzymes. See also Restriction enzymes Enzymes, 5 201... 

Several hundred restriction enzymes have been isolated and characterized. Nomenclature for the enzymes consists of a three-letter abbreviation representing the source (Eco — E. colt), a letter representing the strain (R), and a roman numeral designating the order of discovery. fcoRI is the first to be isolated from E. coli (strain R) and characterized. Table E15.1 lists several other restriction enzymes, their recognition sequence for cleavage, and optimum reaction conditions. 

Nomenclature Restriction enzymes are isolated from bacteria, where they play a role in protecting the host cell against virus infection. Over 100 restriction enzymes have now been isolated and have been named according to the bacterial species from which they were isolated. The first three letters of the enzyme name are the first letter of the genus name and the first two letters of the species name. Since each bacterium may contain several different restriction enzymes, a roman numeral is also used to identify each enzyme. EcoRI, for example, was the first enzyme isolated from Escherichia cgli. 

Protein enzymes have been classified into six major classes according to the nature of the reaction they catalyze. Enzyme Commission (EC) numbers have been assigned to all enzymes by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology. Generally, each enzyme has a unique number, but there are exceptions—the restriction enzymes which cut nucleic acids are one such exceptional group. The official name and munber for this group of enzymes (and there are thousands of them) is Type II site-specific deoxyribonuclease, EC 3.1.21.4. Many other details of enzymes and their kinetics are given in Chap. 5. 

The NC-IUBMB has introduced a number of changes in the terminology following the proposals made by Barrett, Rawlings and co-workers [7] [8]. The term peptidase should now be used as a synonym for peptide hydrolase and includes all enzymes that hydrolyze peptide bonds. Previously the term peptidases was restricted to exopeptidases . The terms peptidase and protease are now synonymous. For consistency with this nomenclature, the term proteinases has been replaced by endopeptidases . To complete this note on terminology, we remind the reader that the terms cysteine endopeptidases and aspartic endopeptidases were previously called thiol proteinases and acid or carboxyl proteinases , respectively [9],... 

Additional information <1, 2> (this group of enzymes is under review by NC-IUBMB, recommendation for a nomenclature system based on acceptor amino acid specificity rather than on protein substrate. In accordance with this system protein-tyrosine kinases would belong to EC 2.7.1 l.X, <1,2> [1] The present data set is restricted to a literature review and does not contain a complete description of kinases. Classification system based on kinase domain phylogeny revealing families of enzymes with related substrate specificities, <1,2> [3]) [1, 3]... 

Smith, H. O. and Nathans, D. 1973. Letter A suggested nomenclature for bacterial host modification and restriction systems and their enzymes. /Mo/Biol, 81 419-23. 

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