The lipase from Pseudomonas mendocina 3121-1 was found to be homogeneous with a molecular mass of 30 kDa by SDS/PAGE. It is composed of two identical subunits. A molecular mass of 62 kDa was determined by gel chromatography on a Toyopearl HW-55F column. Some physicochemical properties of the lipase were investigated using p-nitrophenyl butyrate (p-NPB), Tween 80 solution and Sigma olive-oil emulsion as substrates. The optimum temperature was determined to be 52 degrees C with p-NPB, in the range 50-60 degrees C with Tween 80 and in the range 50-65 degrees C with olive-oil emulsion. The optimum pH was determined to be in the pH range 7.2-7.5, both with Tween and the emulsion, but was unusually alkaline (pH 9.5) with p-NPB. The enzyme was activated for p-NPB hydrolysis by thermal treatment up to 60 min at 60 degrees C, pH 7.0-8.2, but was rapidly inactivated at 70-80 degrees C and at pH 7.0. The lipase was shown to be more thermolabile at 60 degrees C with respect to other two substrates. Using the emulsified substrate, no activity was obtained after preincubating the enzyme for 30 min at 70 degrees C. The enzyme was found to be pH-tolerant when stored at 20 degrees C, pH 6.3-10.3 (100 mM Briton-Robson buffer) as the half-life (t(1/2)) was more than 240 h when p-NPB was used as the substrate. By contrast, the pH-stability range was more narrow (pH 8.0-10.5) with olive-oil emulsion. The effect of various metal ions and EDTA depended on the nature of the substrate.

Summary. Objective. To determine the effect of surgical treatment and red blood cell transfusion on the parameters of antioxidative and immune systems in patients withMedicina (Kaunas) 2009; 45(10)

Lipases of different origin were screened for substrates and different reactions from the practical approach to search for the optimal conditions for biodiesel component production. The commercial lipases under analysis were shown to be specific to p-nitrophenyl fatty acid esters of medium chain length, although Lipolase100 LEX also showed a relatively high hydrolytic activity on p-nitrophenyl palmitate. The soluble Enterobacter aerogenes lipase was shown also to be the most active when hydrolysing medium-chain-length p-nitrophenyl fatty acid esters. The specificity of immobilized commercial lipases did not change as compared with soluble analogues. The immobilized Enterobacter aerogenes lipase showed no significant differences of activity towards p-nitrophenyl butyrate and medium-chain p-nitrophenyl fatty acid esters versus the attached enzyme on polyurethane and chitosan and also showed the highest hydrolytic activity on p-nitrophenyl caprylate as for soluble lipase. Enterobacter aerogenes lipase-catalyzed esterification of oleic acid with oleoyl alcohol was a long-lasting process still in progress after 91 hours. The lipase showed the highest catalytic activity when esterifying oleic acid with ethanol and 1.2-ethanediol. The enzyme slightly esterified the acid with 1.3-propanediol and was almost inactive for esterification with 2-hydroxyethyl ether. Enterobacter aerogenes lipase more efficiently hydrolysed camelina oil than rapeseed oil, considering the former to be an alternative source to be converted into biodiesel components. Methanolysis of rapeseed oil catalyzed by the lipase adsorbed on chitin was also a long-lasting process still in progress during 124 hours. The optimal glycerol-tricaprylate-to-methanol ratio was 1 : 1 for methanolysis of the substrate catalysed by Resinase HT lipase immobilized on a polyurethane support. The lipase was completely depressed at the ratio 1 : 3.

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A more detailed analysis of Pseudomonas mendocina 3121-1 lipase catalytic activity in hydrolysing non-ionic detergents Tweens was the goal of the present study. Tweens as lipase substrates were used in aqueous media at the following final concentrations: half of the critical micelle concentration (CMC), close to CMC, five-fold above CMC and by far exceeding CMC (11-44 mM). The intensity of the hydrolysis of the detergents increased with increasing fatty acid chain length in the Tween structure. The reaction rate also depended on the detergent concentration and changed (increased) at the point when it exceeded the CMC, suggesting that Tweens at those concentrations are not well suitable for stabilizing the Ps. mendocina lipase substrate emulsion.The role of ionic detergents in the lipase-catalysed hydrolysis of soluble substrate p-nitrophenyl butyrate (p-NPB) was also investigated. The hydrolytic activity was shown to be rapidly declined by sodium dodecylsulphate (SDS) during the first 10 min, slower inactivated by dodecyltrimethylammonium bromide (DTMAB) and only slightly affected by sodium deoxycholate (SDCh). The inactivation rate constants (k inact , min -1 ) were calculated to be 0.29, 0.07 and 0.006 for SDS, DTMAB and SDCh, respectively.