Enzyme Commission nomenclature

ENZYME COMMISSION NOMENCLATURE ENZYME CONCENTRATION EFFECTS... 

ENZYME COMMISSION NOMENCLATURE ISOMERIZATION Isomerization mechanisms,... 

ENZYME COMMISSION NOMENCLATURE LYATE ION LYONIUM ION LEVELING EFFECT Lysine,... 

All enzymes already mentioned, except oligo-D-galactosiduronate hydrolase, are included in the Enzyme Nomenclature of the IUPAC-IUB Enzyme Commission,11 and their code numbers and suitably modified, systematic names are used herein. 

Table 3.1 Major classes in the Enzyme Commission system for enzyme nomenclature...

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... 

Enzymes are usually named with reference to the reaction they catalyze. It is customary to add the suffix -ase to the name of its major substrate. The Enzyme Commission (EC) has recommended nomenclature of enzymes based on the six major types of enzyme-catalyzed reactions (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. 

To bring some consistency to the classification of enzymes, in 1964 the International Union of Biochemistry established an Enzyme Commission to develop a nomenclature for enzymes. Reactions were divided into six major groups numbered 1 through 6 (Table 8.3). These groups were subdivided and further subdivided, so that a four-digit number preceded by the letters EC for Enzyme Commission could precisely identify all enzymes. 

EC nomenclature for enzymes A classification of ENZYMES according to the Enzyme Commission of the International Union of Biochemistry and Molecular Biology. Enzymes are allocated four numbers, the first of which defines the type of reaction catalyzed the next two define the substrates, and the fourth is a catalogue number. Categories of enzymes are EC 1, oxidoreduc-tases EC 2, transferases EC 3, hydrolases EC 4, lyases EC 5, isomerases EC 6, ligases (Synthetases). 

Today, more than 2300 different enzymes are catalogued by the Enzyme Commission of the International Union of Biochemistry (TUB). The enzyme nomenclature proposed by the lUB uses the name of the substrate (the material that is affected by the enzyme) followed by the suffix ase . For example, the enzymes affecting amylum (Latin for starch ) are called amylases. Enzymes affecting lipids, cellulose and proteins are named lipases, cellulases and proteases, respectively. However, many enzymes are still named by their original names. Diastase, trypsin, papain, lactase, etc. are examples of old names which were used before the official TUB names were proposed. Names of proteases originally had the suffix in and are still in use in the traditional industries such as breweries and bread bakeries. 

A systematic scheme of nomenclature for enzymes was proposed by the International Enzyme Commission in 1964. They are now categorized into six major classes depending on the type of chemical reaction that they catalyze. 

A large number of different enzymes has been described. Their nomenclature has been rather haphazard, although many enzymes are named by placing -ase after their substrate others are called product synthetase. Enzymes that transfer phosphate from ATP to a substrate are called substrate kinase. An international enzyme commission (EC) has developed a classification number, a systematic name, and a recommended name. Recommended names are widely used, but the EC numbers and systematic names are increasingly used to avoid confusion, often in a footnote. 

In accordance with the nomenclature recommended by the Enzyme Commission of the International Union of Biochemistry these enzymes have received the following systematic names ... 

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. 

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. 

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