engleski

Extracellular lipase from bacterium Streptomyces rimosus

Lipases (triacylglycerol acylhydrolases) constitute a diverse and ubiquitous family of enzymes, that initiate the catabolism of fats and oils in biological systems. They remain active in a variety of organic solvents, where they can catalyze transformations other than the hydrolytic reaction by which they are defined. Microbial lipases have recently attracted considerable attention owing to their biotechnological potential, ranging from the use in laundry detergents to stereospecific biocatalysis. As various industrial applications require specific properties of lipases, there is still an interest for discovery of new lipases, that could create new applications. Streptomycetes are gram-positive soil bacteria, that exhibit remarkable capacity for synthesis of secondary metabolites, and that use a wide variety of extracellular hydrolytic enzymes (among them lipases) to degrade organic material in the soil. However, only a few streptomycetes' lipases have been analyzed so far. We have purified an extracellular lipase from the culture filtrate of Streptomyces rimosus by chromatography on the columns of DEAE-cellulose, CM-cellulose, hydroxylapatite, Mono S (FPLC) and Sephadex G-75 Superfine. The hydrolysis of p-nitrophenyl-palmitate was used for detection of the lipase activity. The purified lipase was shown to be a monomeric (Mr 27500), basic protein (pI 8.45), stable in the range of pH 4-10, and optimally active at pH 10.0. It was partially inhibited by the serine-specific inhibitor phenylmethylsulphonyl fluoride and by the reducing agent 1,4-dithiothreitol. According to its properties, S. rimosus lipase differed from the already characterized microbial enzymes.

Streptomyces rimosus; lipase; isolation; properties

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