Numbers Enzyme Commission

Enzyme CAS Registry Number Enzyme commission number Catalysis Use... 

EC - Enzyme Commission number system W - indicates the reaction catalysed (1—6)... 

The criteria for gene displacement in this study were strict. The reactions catalyzed were required to have the same EC (Enzyme Commission) number, which implies that the same cofactors had to be involved. In the example of reactions involved in the citric acid cycle given previously, when only the carbohydrate substrate and product of the reaction were the same, we could identify gene displacements at 6 of the 11 steps included in the analysis. Only two of those (malate dehydrogenase and fumarase) met the criteria in Galperin et al. (1998). 

More than 2000 different enzymes are currently known. A system of classification has been developed that takes into account both their reaction specificity and their substrate specificity. Each enzyme is entered in the Enzyme Catalogue with a four-digit Enzyme Commission number (EC number). The first digit indicates membership of one of the six major classes. The next two indicate subclasses and subsubclasses. The last digit indicates where the enzyme belongs in the subsubclass. For example, lactate dehydrogenase (see pp. 98-101) has the EC number 1.1.1.27 (class 1, oxidoreductases subclass 1.1, CH-OH group as electron donor sub-subclass 1.1.1, NAD(P) " as electron acceptor). 

In the literature of PVA biodegradation, the orientation with respect to the enzymatic activities that are described is not clear-cut and sometimes even perplexing. This originates in the historical development of the field that gave rise to the nomenclature used today. Table 2 aims to give a clear denomination of the enzymes that are directly involved in the biodegradation of PVA, and that are cited in the literature so far. As an unambiguous denomination for enzyme activity, the Enzyme Commission number (EC number) is used. Every EC number is... 

Enzyme Commission number Name used herein Other names Reaction catalyzed... 

In addition to the metabolic databases listed above, some of the enzyme databases described in the previous chapter (Chapter 6) also serve as useful metabolic resources. All of the enzyme and metabolic databases make use of EC (Enzyme Commission) numbers which are available at the International Union of Biochemistry and Molecular Biology (IUBMB) site (http //www.chem.qmw.ac.uk/ iubmb/enzyme/). 

During natural evolution, a broad variety of enzymes has been developed, which are classified according to the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (IUBMB). Thus, for each type of characterized enzyme an EC (Enzyme Commission) number has been provided (see http // www.expasy.ch/enzyme/). For instance, all hydrolases have EC number 3 and further subdivisions are provided by three additional digits, e.g. all lipases (official name triacylglycerol lipases) have the EC number 3.1.1.3 and are thus distinguished from esterases (official name carboxyl esterases) having the EC number 3.1.1.1. This classification is based on the substrate (and cofactor) specificity of an enzyme only, however often very similar amino acid sequences and also related three-dimensional structures can be observed. 

Concise, basic enzyme data is recorded for some 800 enzymes including the Enzyme Commission number, trivial name, systematic name, reaction catalyzed, equilibrium constant, molecular weight, specific activity, specificity, Michaelis constants, inhibitors, light absorption data, and references. Where required, conditions, source, etc. are specified. 

This volume provides recommendations which serve to classify known enzymes by listing the Enzyme Commission number, the various names for each enzyme, the reaction catalyzed, brief comments, and selected references. There is no attempt to do more than classify. 

Common name of enzyme Systematic name of enzyme Enzyme Commission number... 

A-17 According to lUB system enz)mies are grouped in six major classes. Each with sub classes based on the t) e of reaction catalyzed. Systemic classification of enzymes based on numbering system is used. Each enzyme is assigned a code number or EC (enzyme commission number) four-digit classification number and a systematic name, which identifies the reaction catalyzed. 

When searching for a drug in MEDLINE, it is best to use a generic name. The U.S. Adopted Names are preferred, as the brand name can only be searched for if it is in the title or abstract of the original article. However, since June 1980, the NLM has added other searchable fields to ease drug searching. It is now possible to search on CAS registry numbers. Enzyme Commission Numbers, and the substances of those numbers. 

When searching for a drug the U.S. Adopted Name is the first choice, but since 1998 it is also possible to search using CAS registry numbers. Note that it is only possible to search on the fields of brand names. Enzyme Commission Numbers and lab codes if they are given in the original literature source. The indexers at BioSciences Information Service will not add them to the database. 

Fig. 8. —Enzymic Reactions Concerned with the Conversion of D-Galactose into D-Glucose 6-Phosphate. (Enzyme Commission numbers are given for each enzyme.)...

In this Section, the term xylanase will refer to those enzymes capable of hydrolyzing the (1 — 4)-/3-D-xylopyranosyl linkages of the (1 — 4)-/3-D-xylans, namely, arabinoxylan, arabinoglucuronoxylan, arabino-4-O-methyl-D-glucuronoxylan, and glucuronoxylan. D-Xylanases of this type have been assigned the Enzyme Commission numbers 3.2.1.8 [(1 — 4)-/3-D-xylan xylanohydrolase, endo-xylanase] and 3.2.1.37 [(1 —> 4)-/3-D-xylan xylohydrolase, exo-xylanase]. 

AMP Adenosine monophosphate EC Enzyme Commission number (International... 

Enzyme Commission number first number, major class second number, subclass third number, subsubclass fourth number, serial number. 

According to the first report of the Enzyme Commision from 1961 all enzymes are classified in six enzyme classes, depending on the reaction being catalyzed. Within the scheme of identification each enzyme has an Enzyme Commission number denominated by four numbers after the abbreviation E.C. The first number indicates one of the six possible reaction types that the enzyme can catalyze the second number defines the chemical structures that are changed in this process the third defines the properties of the enzyme involved in the catalytic reaction or further characteristics of the catalyzed reaction the fourth number is a running number. 

This table contains values of apparent equilibrium constants K for selected enzyme-catalyzed reactions at specified temperatures T and pHs. In those cases where the ionic strength I and/or the pMg (pMg = -logjj,[Mg ]) have been reported, the values of these quantities are given. The Enzyme Commission numbers [Webb (1992)] of the enzymes that were used to catalyze the reactions are also given. 

Note EC number = Enzyme commission number. The first three numbers define major class, subclass, and sub-sub class, respectively. The last is a serial number in the sub-sub class, indicating the order in which each enzyme is added to the list (Mathews and van Holde, 1990). 

LocusLink is an NCBI project to link information applicable to specific genetic loci from several disparate databases. Information maintained by LocusLink includes official nomenclature, aliases, sequence accessions (particularly RefSeq accessions), phenotypes. Enzyme Commission numbers, map information, and Mendelian Inheritance in Man numbers. Each locus is assigned a unique identification number, which additional databases can then reference. LocusLink is described in greater detail in Chapter 7. 

Enzyme classification is primarily based on the recommendations of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (lUBMB)", and it describes each type of characterized enzyme for which an EC (Enzyme Commission) number has been provided. EC classes define enzyme function based on the reaction, which is catalyzed by the enzyme. The classification scheme is hierarchical, with four levels. There are six broad categories of function at the top of this hierarchy and about 3500 specific reaction types at the bottom. EC classes are expressed... 

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