Proteinase classification

All the well-characterized proteinases belong to one or other of four families serine, cysteine, aspartic, or metallo proteinases. This classification is based on a functional criterion, namely, the nature of the most prominent functional group in the active site. Members of the same functional family are usually evolutionarily related, but there are exceptions to this rule. We... 

LASKOWSKi M Jr (1986) Protein inhibitors of serine proteinases-mechanism and classification. Adv Exp Med Biol. 199 1-17. 

A. J. Barrett, Introduction The Classification of Proteinases , in Protein Breakdown in Health and Diseases , Ciba Foundation Symposium 75, Eds. D. Evered, J. Whelan, Ex-cerpta Medica, Amsterdam, 1980, p. 1-13. 

Based on their sequence homology, disulfide connectivity, and cysteine location within the sequence and chemistry of the reactive site. Pis can be assigned to distinct families, as classified by Laskowski and Kato. Kunitz-type, Bowman—Birk-type, Potato type I and type II, and squash inhibitors are members of these families shown in Table 3. For inhibitors not falling into these classifications more families have been proposed. Pis can also be classified by their target/mode of action. Plants have been found to express Pis that target serine proteinases, cysteine proteinases, aspartic proteinases, and metallo-proteinases. Serine and cysteine protease inhibitors are the best-studied PIs. ... 

Classincation of the Proteases. The classification of the proteases is based on their mechanism of catalysis (4), The four primary classes of proteases are the serine, aspartic, cysteine, and metalloproteases (5). This classification is based on the primary functional group found in the en me s active site. There are likely to be other proteases eventually characterized which will not precisely fit into this categorization scheme and additional categories will be needed. One example of a potential new category is the ATP-dependent proteinases (6), a group of proteinases which require ATP for activity. 

L. Polgfr. Problems with the classification of papaya proteinases. Biochem. J. 

B3. Barrett, A. J., Fritz, H., Grubb, A., Isemura, S., Farvinen, M., el al., Nomenclature and classification of the proteins homologous with the cysteine-proteinase inhibitor chicken cystatin [letter]. Biochem. J. 236(1), 312 (1986). 

Biochemical characterization of Prps<> reveals heterogeneity in the polypeptide patterns among the human prion diseases and this has been useful for the molecular classification of PrP " (reviewed by Gambetti et al., 2003). Limited proteinase K... 

The first nonpeptide, irreversible inactivators of serine proteinases were phosphoryl fluoride derivatives such as diisopropylphosphofluoridate (see Figure 2.7) [168]. It was shown that the phosphofluoridates stoichiometri-cally inactivate serine proteinases, by coupling with the active-site serine hydroxyl group. They have since been used as a diagnostic tool for the classification of serine proteinases. Similarily, both aryl and aralkyl sulphonyl fluorides were determined to be inactivators, forming a sulphonyl enzyme derivative at Ser-195 which is resistant to hydrolysis. 

It was suggested (Puhvel and Reisner, 1972) that hyaluronidase can split extracellular substances of the cell wall of sebaceous ducts and thus increase the permeability of epithelial follicles. Neuraminidase can damage cell and tissue membranes, affecting the sialic acid residues on the surface of the cells. Under the action of proteases of P. acnes, which also possesses keratinolytic activity, small chemotactic peptides are produced that may have a role in the onset of inflammation. Proteolytic activity may be significant (Ingham, 1983) in complement activation. It was shown (Ingham, 1983) that a preparation of extracellular proteases from P. acnes P-37 contained at least three types of proteases with different molecular masses. The secretion of proteinases is used as a criterion in the classification of these bacteria. 

The classification outlined here is presented mainly for convenience in arranging and relating a wealth of material. Enzymes display an amazing specificity in the reactions each will catalyze. Despite this, these classifications do not represent absolutes in specificity. Some proteinases will, for instance, catalyze the hydrolysis of amino acid esters and amides as well as peptides. 

The definition of the scope of the specificity of proteolytic enzymes with regard to the chemical configurations in the vicinity of the hydrolyzable peptide bond has necessarily been restricted to their peptidase activity in order that substrates of known chemical structure can be used. The familiar classification of proteinases on the basis of specificity towards peptides as model substrates, ss, 84, 85 meet rigorous testing on those rare... 

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