The production and characterization of lipases from a micrococcus and a pseudomonad.

Abstract

SUMMARY: Extracellular lipase production was a constitutive property of the micrococcus and pseudomonad studied but was considerably influenced by nutritional and physical conditions. The lipase in culture supernatant fluids of the micrococcus was markedly heat resistant but became increasingly more ther-molabile with the degree of purification obtained. The hydrolytic activity of partially purified extracellular lipase preparations from each organism was due to a single protein which was identical with a hydrolytic enzyme also found in cell-free extracts of each organism. The lipases from both organisms had general specificity towards ester linkages although the lipase from the micrococcus was markedly more active towards esters containing short chain fatty acids and comparatively less active towards trigylcerides containing long chain acids than was the pseudomonal lipase. The activity of both lipases showed an optimum for all substrates at pH 8.0-8.5 and did not decrease at higher pH values, indicating the involvement of an acidic group in the enzyme/substrate binding. The results of inhibition studies were consistent with the view that both lipases possess a serine-imidazole active centre and are therefore similar to esterolytic enzymes in mammalian systems.