Enzymes, classification specific

Arylsulfatase [EC 3.1.6.1 ], also known simply as sulfatase, catalyzes the hydrolysis of a phenol sulfate, thereby producing a phenol and sulfate. This enzyme classification represents a collection of enzymes with rather similar specificities. (1) Steryl-sulfatase [EC3.1.6.2],also referred to as arylsulfatase C and steroid sulfatase, catalyzes the hydrolysis of 3-j8-hydroxyandrost-5-en-17-one 3-sulfate to 3-j8-hydroxyandrost-5-en-17-one and sulfate. The enzyme utilizes other steryl sulfates as substrates. (2) Cere-broside-sulfatase [EC 3.1.6.8], or arylsulfatase A, catalyzes the hydrolysis of a cerebroside 3-sulfate to yield a cerebroside and sulfate. The enzyme will also hydrolyze the galactose 3-sulfate bond present in a number of lipids. In addition, the enzyme will also hydrolyze ascorbate 2-sulfate and other phenol sulfates. 

The names of the examples of textile-relevant enzymes follow the nomenclature of Duclaux from 1898, characterising an enzyme by the end-syllable ase , added to the name of the snbstrate that is split, synthesised or otherwise catalysed. As with all catalysts, enzymes reduce the activation energy of a specific reaction. The discovery of large qnantities of new enzyme systems afforded a more differentiated nomenclatnre, realised in 1964 by the International Union of Pure and Applied Chemistry (lUPAC) and the International Union for Biochemistry (lUB). In the new enzyme classification (EC) the first nnmber refers to one of the six main gronps and the following numbers to subgroups, for example EC 3.4.S.6, where 3 stands for hydrolases. ... 

The immunohistochemical demonstration of the specific endocrine cell peptides allows the classification of the pancreatic endocrine neoplasms (PENs). However, it is not always possible to demonstrate these in PENs. Therefore it is of diagnostic importance to use broad-spectrum endocrine cell markers for the general identification of the endocrine nature of islet cells and PENs. These protein markers, localized in the secretory granules in the cytosol or in the cellular membrane, are present in most (rarely in all) normal and neoplastic endocrine cells. The markers most commonly used in routine histopathology have been the secretory granule proteins chromogranin and synaptophysin and the cytosolic enzyme neuron-specific enolase (NSE). Of these, chromogranin is the most specific but its sensitivity is about 80% to 90% (Fig. 15.2). 

Hundreds of potentially useful enzymes are available in nature. It is often worthwhile to survey enzymes for applicability in the synthesis of a specific compound, but how to find the best enzyme Enzymes have been reviewed and classified by many schemes12-41. Enzymes involved in reactions at phosphoryl groups are, unfortunately for the synthetic chemist, spread almost over all classes. Without a good knowledge of enzymology, it is not easy to find the enzyme classes of interest for a particular transformation. This review links the compound classes and enzyme classification systems in Section 13.1.1 to help overcome this barrier. 

Complete enzyme names and enzyme classification numbers with an indication of a protein family for those enzymatic roles that are known to be encoded by more than one protein family (nonorthologous displacements). Note that some protein families may have more than one relevant enzymatic role, either due to a broad specificity (e.g., NadM family having both NMNAT and NaMNAT activities) or due to the presence of more than one functional domain (e.g., NadR family containing NMNAT and RNMKIN domains). 

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... 

A third edition of the well-known book Enzymes by Dixon and Webb reflects the changes and developments which have occurred in the area of enzyme chemistry. Enzyme techniques, isolation, kinetics, classification, specificity, mechanisms, inhibition and activation, co-factors, structure, biosynthesis, and biology are all covered. Most of the material has been rewritten but, despite the wealth of new material included, the book retains the general form of the previous editions. 

Therefore, enzyme reaction specificity rather than substrate specificity is considered as a basis for enzyme classification and nomenclature (cf. 2.2.6). 

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. 

Immunoaffinity chromatography (IAC), 6 400—402 12 137, 145 Immunoanalyzers, automated, 14 150 Immunoassay(s), 14 135-159. See also Immunoassay- DNA probe hybrid assays Immunoassay methods Immuno(bio)sensors antibody-antigen reaction, 14 136-138 basic technology in, 14 138-140 chemiluminescent, 14 150-151 classification of, 14 140-153 design of, 14 139-140 enzyme, 14 143-148 fluorescence, 14 148-150 highly specific, 14 153 historical perspective on, 14 136 microarrays and, 14 156—157 microfluidics in, 26 968—969 monoclonal versus polyclonal antibodies in, 14 152-153... 

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/. 

One of the general principles of the Nomenclature Committee is that enzymes should be classified and named according to the reaction they catalyze. However, the overlapping specificities of and great similarities in the action of different peptidases render naming solely on the basis of function impossible [10]. For example, some enzymes can act as both endo- and exopeptidases. Thus, cathepsin H (EC 3.4.22.16) is not only an endopeptidase but also acts as an aminopeptidase (EC 3.4.11), and cathepsin B (EC 3.4.22.1) acts as an endopeptidase as well as a peptidyl-dipeptidase (EC 3.4.15). The actual classification of peptidases is, therefore, a compromise based not only on the reaction catalyzed but also on the chemical nature of the catalytic site, on physiological function, and on historical priority. 

The evolutionary classification has a rational basis, since, to date, the catalytic mechanisms for most peptidases have been established, and the elucidation of their amino acid sequences is progressing rapidly. This classification has the major advantage of fitting well with the catalytic types, but allows no prediction about the types of reaction being catalyzed. For example, some families contain endo- and exopeptidases, e.g., SB-S8, SC-S9 and CA-Cl. Other families exhibit a single type of specificity, e.g., all families in clan MB are endopeptidases, family MC-M14 is almost exclusively composed of carboxypeptidases, and family MF-M17 is composed of aminopeptidases. Furthermore, the same enzyme specificity can sometimes be found in more than one family, e.g., D-Ala-D-Ala carboxypeptidases are found in four different families (SE-S11, SE-S12, SE-S13, and MD-M15). 

Some aspects of the sequence classification of esterases need clarification [87]. In the case of ES4, two separate forms were purified and found to have virtually identical specificity and chemical properties. The enzymes ES8 and ES10 appear to be a monomer and a dimer, respectively, of the same enzyme, and ES9 is probably a combination of ES7 and ES8/10 [88]. For esterase ESI5, different p/ values have been reported by different authors. 

Phosphatases are numerous and important enzymes (see also Chapt. 2). They are classified as phosphoric monoester hydrolases (phosphatases, EC 3.1.3), phosphoric diester hydrolases (phosphodiesterases, EC 3.1.4), triphosphoric monoester hydrolases (EC 3.1.5), diphosphoric monoester hydrolases (pyrophosphatases, EC 3.1.7), and phosphoric triester hydrolases (EC 3.1.8) [21] [63]. Most of these enzymes have a narrow substrate specificity restricted to endogenous compounds. However, some of these enzymes are active toward xenobiotic organophosphorus compounds, e.g., alkaline phosphatase (EC 3.1.3.1), acid phosphatase (EC 3.1.3.2), aryldialkylphosphatase (para-oxonase (PON1), EC 3.1.8.1) and diisopropyl-fluorophosphatase (tabunase, somanase, EC 3.1.8.2) [64 - 70]. However, such a classification is far from definitive and will evolve with further biochemical findings. Thus, a good correlation has been found in human blood samples between somanase and sarinase activities on the one hand, and paraoxonase (PON1) type Q isozyme concentrations on the other [71]. 

Both are entities in well-defined languages that represent specific abstractions SMILES, the valence model of a molecule ECN, a classification of enzyme functionality. 

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