engleski

The SGNH-lipolytic enzymes in Streptomyces species

Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) are hydrolytic enzymes widely distributed in microorganisms, plants and animals. Microbial lipases from a wide range of species have been subject of many important studies in the past few years because of the large number of reactions they catalyze. Streptomyces species are the best known for their production of a variety of types of antibiotics. However, these bacteria also produce numerous compounds of other bioactivities and therefore represent a group of industrially important microorganisms. The available genome data bases for streptomycetes predicted a large number of genes encoding enzymes of different lipolytic activities (approximately 50-80). Although these data point out the potential for synthesis of a broad spectrum of lipases, only a few have been studied and reported. The main object of our studies over several years have been GDS(L)/SGNH lipases from streptomycetes. These enzymes often display multifunctional properties with high potential for use in industry and environmental applications ; however they have been poorly investigated so far. Three GDS(L) lipases from genus Streptomyces were cloned. Two genes encoding lipases from S. rimosus (Q93MW7, SrL) and S. coelicolor (SCO1725, Sc1) were expressed and the lipases were purified from heterologous host. SrL and Sc1 were extensively biochemically characterized and the properties of these enzymes were compared. These enzymes might have significant biotechnological potential due to high working temperature ; stability in organic solvents, 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, as shown by CD spectroscopy. Based on the protein sequence alignment the amino acid residues important for the catalytic activity were predicted and the results obtained after site-directed mutagenesis will be presented.

SGNH-lypolytic enzymes; Streptomyces; GDS(L) lipases

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