A Method for Determination of Interesterification Activity of Biocatalysts

The study of 1–3 regioselective interesterification of melted fats catalysed by lipases, worked as various catalytic preparations, involves a special assay for activity determination allowing trustworthy and significative comparisons between the different biocatalysts. The reference system is the mixture methyl stearate and coconut oil. It has been shown that hydrolytic activity determined as usual, is completely independent from the interesterification activity expressed in micromole of lauric acid incorporated in the methyl stearate per minute and per gramme of biocatalyst. Water activity (aw) also plays an important role in the course of the reaction; aw must be maintained under 0.5.     

Purification and properties of the lipase fromCandida deformans (zach) langeron and guerra

Palm oil being solid at room temperature could be converted into a fluid oil by substitution of about 40–50% of its palmitic acid. This could be achieved by a fermentation process or using yeast lipase. Candida deformans CBS 2071 seemed suitable for this purpose: therefore, its lipase was isolated and studied. This enzyme was purified by acetone precipitation followed by chromatographies on Sephadex C 50 and Sephadex G 150. The purification factor achieved was ×70, and the protein and activity yields were 0.25% and 18%, respectively. The homogeneity of the purified enzyme was verified by polyacrylamide gel electrophoresis. The enzyme molecular weight was estimated at 207,000. Its activity is optimal between 40 C and 50 C and its optimum pH is 7.0. This enzyme is thermo-resistant and loses only 14% and 18% of its activity, respectively, when heated to 45 C and 55 C for 30 min. Its activation energy was 2.75 kcal.mole^?1 and its inactivation energy was around 21 kcal.mole^?1. This enzyme is activated by Ca⁺⁺, Mg⁺⁺ and Co⁺⁺ and inhibited by Cu⁺⁺, Zn⁺⁺, and p-chloromercuribenzoate (pCMB) and EDTA. The synthesis of this lipase is induced by lipid substrates in the culture medium and inhibited by glucose. This enzyme attacks primarily the 1- (or 3-) position of all triglycerides tested. Hydrolysis was preferential for triglycerides containing short chain fatty acids. The triglycerides with monounsaturated monoacids were more quickly hydrolyzed, than those with saturated monoacids. The presence of two and especially three double bonds in the fatty acid chain seemed to slow down the rate of hydrolysis.