International Union of Biochemistry

Enzymes are classified in terms of the reactions which they catalyse and were formerly named by adding the suffix ase to the substrate or to the process of the reaction. In order to clarify the confusing nomenclature a system has been developed by the International Union of Biochemistry and the International Union of Pure and Applied Chemistry (see Enzyme Nomenclature , Elsevier, 1973). The enzymes are classified into divisions based on the type of reaction catalysed and the particular substrate. The suffix ase is retained and recommended trivial names and systematic names for classification are usually given when quoting a particular enzyme. Any one particular enzyme has a specific code number based upon the new classification. 

International Union of Biochemistry and Molecular Biology, Biochemical Nomenclature and Related Documents, 2nd ed., Pordand Press, London, 1992. 

International Union of Biochemistry, Encyme Nomenclature Recommendations 1964, Elsevier, Amsterdam, The Nethedands, 1965. 

International Union of Biochemistry, Enyme Nomenclature 1978, Academic Press, New York, 1979, Suppl. 1 Eur. / Biochem. 104, 1 (1980). 

A system based partly on historical names, partly on the substrate, and partly on the type of reaction catalyzed is far from satisfactory. In 1956, the International Union of Biochemistry set up a Commission on Enzymes to consider the classification and nomenclature of enzymes. The Commission presented a report in 1961 whose recommendations for naming and classifying enzymes were subsequently adopted (12). Enzymes are classified on the basis of the reactions they catalyze. Despite its apparent complexities, the system is precise and very descriptive, accommodating existing enzymes and serving as a systematic basis for the naming of new enzymes. AH enzymes are placed in one of the six principal classes. 

International Union of Biochemistry and Molecular Biology Nomenclature Committee, 1992. Enzyme Nomenclature. New York Academic Press. A reference volume and glossary on die official classification and nomenclature of enzymes. 

Since the early 1970s a panel convened by the International Union of Pure and Applied Chemistry and the International Union of Biochemistry and Molecular Biology has been working to formulate recommendations for carbohydrate nomenclature that meet developing needs of research and electronic data handling, while retaining links to the established literature base on carbohydrates. The realization of these endeavors is presented here in the final document Nomenclature of Carbohydrates, which provides a definitive reference for current researchers, both in the text version and in the version accessible on the World Wide Web (http //www.chem.qmw.ac.uk/iupac/2carb/), where amendments and revisions are maintained. 

Enzymes catalyzing the hydrolysis of esters are termed esterases. They belong to a larger group of enzymes termed hydrolases, which can cleave a variety of chemical bonds by hydrolytic attack. In the classification of hydrolases of the International Union of Biochemistry (lUB), the following categories are recognized ... 

Classification of Enzymes. A systematic classification and nomenclature has been established by the Commission on Enzymes of the International Union of Biochemistry (6), which divides enzymes into six general groups ... 

The responsibility for enzyme nomenclature is supported by the Nomenclature Committee of the International Union of Biochemistry (IUB now the International Union of Biochemistry and Molecular Biology, IUBMB) and the International Union of Pure and Applied Chemistry (IUPAC). These committees collect information about changes and additions to enzyme nomenclature13"15. 

The term for the saturation rate (Vsat) in earlier works commonly employed as maximum rate (Vrnax) should not - according to the recommendation of the International Union of Biochemistry — be used any more because it does not describe a real maximum, but a limit. 

This corresponds to the recommendations given in 1959 by a joint committee of the Clinical Chemistry Commission of IUPAC (International Union of Pure and Applied Chemistry) and the Enzyme Commission of IUB (International Union of Biochemistry). Thus, one unit of enzyme activity should be defined as that amount of enzyme which catalyzes the conversion of one micromole of substrate per minute under defined conditions (W9). 

In accordance with the recommendation of the Commission of the International Union of Biochemistry [R. H. S. Thompson, Classification and nomenclature of enzymes and coenzymes, Nature 193, 1227 (1902)] the terms NAD and NADP have been used instead of DPN and TPN, except in Fig. 4. The generic term nicotinamide nucleotides is used with the same significance as pyridine nucleotides. 

International Union of Biochemistry and Microbiology, 17 402 Nomenclature of Inorganic Chemistry (IUPAC), 17 392-393, 399 Nomex, 10 211, 212 Nomex aramid, 13 372 Nomex fiber, 13 373 Nominal mass, 15 649, 650 Nonaaquaneodymium(III), 7 578t Nonaborane(15), 4 186... 

Each enzyme has been given a four-digit number by the Enzyme Commission of the International Union of Biochemistry. The first three digits relate to the reaction catalysed by the enzyme and the final one is required if several enzymes with different protein structures catalyse the same reaction. 

Magnetic resonance techniques have again been popular for studying enzymes which are involved in phosphate hydrolysis and transfer. 31P or 19F N.m.r.1-2 and spinlabelling3 have all been used to study the interaction of substrates with these enzymes, while affinity labelling4 5 6 7 is another technique which has been used to obtain information about the sequence and conformation of amino-acid chains at the active sites of enzymes. Recently, these experimental methods have been applied to the study of cell membranes,6-7 and these are mentioned in a new series of books concerned with enzymes in biological membranes.8 A new journal, Trends in Biochemical Sciences, which contains concise, up-to-date reviews on these and other topics is published by Elsevier on behalf of the International Union of Biochemistry. 

The classification adopted by the Nomenclature Committee (NC) of the International Union of Biochemistry and Molecular Biology (IUBMB) divides peptidases into classes and subclasses according to the positional specificity in the cleavage of the peptide link of the substrate. The last publication of the complete printed version of the Enzyme Nomenclature was in 1992 [1][2], but a constantly updated version with supplements is available on the World Wide Web at http //www.chem.qmul.ac.uk/iubmb/enzyme/. Similarly, all available Protein Data Bank (PDB) entries classified as recommended by the NC-IUBMB can be found on the WWW at http //www.bio-chem.ucl.ac.uk/bsm/enzymes/. 

Enzyme Nomenclature, International Union of Biochemistry, Academic Press, 1982. 

Webb EC, editor. Enzyme nomenclature 1992. San Diego International Union of Biochemistry and Molecular Biology/Academic Press, 1992. 

Nonproductive reversible complexes of an enzyme with various substrates and/or products. The International Union of Biochemistry distinguishes dead-end complex from abortive complex, and the latter term is regarded... 

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