The Action of Microorganisms on Fats. II. Some Characteristics of the Lipase System of Penicillium Roqueforti

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Abstract
The lipolytic activity of 2 enzyme prepns. was studied, one obtained from the mycelium and the other from the medium on which the mold was cultured. Titration procedures were used to determine lipolytic activity. The temp. optima of the mycelial and medium prepns. on tri-butyrin and butterfat were between 30[degree] and 32 C. with a reaction time of 1 hr. in acetate buffer at pH 5.0. At low temps. increase in temp. increased the rate of hydrolysis markedly. The pH-activity curves as influenced by a variety of exptl. conditions were descr. The pH obtained were as follows: [image]med. prepn., pH 7.0 to 7.8 on tributyrin and pH 6.5 to 6.8 on butter-fat; mycelial prepn., pH 6.0 to 6.7 on tributyrin and pH 7.0 to 7.2 on butterfat. The lipolytic enzymes present in these 2 prepns. show much greater relative specificity for triglycerides than for ethyl esters. There was consistently a faster rate of hydrolysis by the enzyme system acting on tributyrin than on any other substrate used. The activity was also greater on ethyl butyrate than on the other ethyl esters studied. The activity of the lipase system on butterfat fell within the range of activities found on tricaproin, tricaprylin, and trilaurin. It was about 1/3 as active on butterfat as it was on tributyrin. The activity of this lipase system de-creased as the molecular wt. of the fatty acid esterified with the alcohol increased. An increase in NaCl concn. decreased the activity of this lipase system.