engleski

The power of SGNH-lipases from Streptomyces

Lipases are widely distributed in microorganisms, plants and animals. In the past few years, these enzymes from a wide range of microbial species have been studied because of the large number of reactions they catalyze. Streptomyces species are the best known for their production of variety of antibiotics. However, they also produce numerous other bioactive compounds and represent a group of industrially important microorganisms. The genome data bases for streptomycetes predicted a large number of genes encoding enzymes of different lipolytic activities (app. 50-80). Although these data point out that these bacteria have great potential for synthesis of a broad spectrum of lipases, only a few have been studied and reported so far. The main object of our studies over several years has been SGNH-lipases from streptomycetes. These enzymes are interesting but still poorly characterized. They often display multifunctional properties such as broad substrate and regiospecificity. They have flexible active site that appears to change conformation with the presence and binding of various substrates. These enzymes do not exhibit high sequence homology. They have five short consensus motifs among which a distinct GDSL motif with catalytic serine residue is located near the N-terminus. Two lipases from S. rimosus and S. coelicolor were purified from heterologous host and extensively biochemically characterized. Their properties were compared and will be disscused. These enzymes might have significant biotechnological potential due to high working temperature ; stability in organic solvents, activity over a broad range of pH and temperature, and the ability to hydrolyze numerous classes of substrates. Although the structures of enzymes have not been solved, both enzymes are predominantly α-helical proteins. The amino acid residues important for the catalytic activity were predicted, mutated and the activities of wild type enzyme and mutants were analyzed.

SGNH-lipases; Streptomyces

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