COMPOSITION OF A CRUDE LIPASE FROM CANDIDA-CYLINDRACEA AS STUDIED BY DIFFERENTIAL SCANNING CALORIMETRY AND THERMOGRAVIMETRY

Lipases are carboxyl-esterases (EC 3.1.1.3.) which, in vivo, catalyze the hydrolysis of triglycerides and isoluble substrates by a heterogen eous process. In vitro, they may also hydrolyze soluble esters, but th e presence of a water-lipid interface significantly increases their li polytic activity. The commercially available crude lipase contains ca. 30% of lactose as 'extender'. In fact, the addition of sugars or poly ols stabilizes the biological macromolecules, thereby preventing loss of enzyme activity and increasing resistance to denaturing conditions. By means of differential scanning calorimetry (DSC) and thermogravime try (TG), it has been possible to evaluate the composition of a commer cial lipase and also to demonstrate the addition of a monohydrate alph a-lactose, and the time of addition. (C) 1998 Elsevier Science B.V.