MOLECULAR AND BIOTECHNOLOGICAL ASPECTS OF MICROBIAL PROTEASES

Proteases represent the class of enzymes which occupy a pivotal positi on with respect to their physiological roles as well as their commerci al applications. They perform both degradative and synthetic functions . Since they are physiologically necessary for living organisms, prote ases occur ubiquitously in a wide diversity of sources such as plants, animals, and microorganisms. Microbes are an attractive source of pro teases owing to the limited space required for their cultivation and t heir ready susceptibility to genetic manipulation Proteases are divide d into exo- and endopeptidases based on their action at or away fi om the termini, respectively. They are also classified as serine protease s, aspartic proteases, cysteine proteases, and metalloproteases depend ing on the nature of the functional group at the active site. Protease s play a critical role in many physiological and pathophysiological pr ocesses. Based on their classification, four different types of cataly tic mechanisms are operative. Pretenses find extensive applications in the food and daily industries. Alkaline proteases hold a great potent ial for application in the detergent and leather il industries due to the increasing trend to develop environmentally friendly technologies. There is a renaissance of interest in using proteolytic enzymes as ta rgets for developing therapeutic agents. Protease genes from several b acteria, fungi, and viruses have been cloned and sequenced with the pr ime aims of (i) overproduction of the enzyme by gene amplification, (i i) delineation of the role of the enzyme in pathogenecity, and (iii) a lteration in enzyme properties to suit its commercial application. Pro tein engineering techniques have been exploited to obtain proteases wh ich show unique specificity and/or enhanced stability at high temperat ure or pH or in the presence of detergents and to understand the struc ture-function relationships of the enzyme. Protein sequences of acidic , alkaline, and neutral proteases from diverse origins have been analy zed with the aim of studying their evolutionary relationships. Despite the extensive research on several aspects of proteases, there is a pa ucity of knowledge about the roles that govern the diverse specificity of these enzymes. Deciphering these secrets would enable Its to explo it proteases for their applications in biotechnology.