EFFECT OF POLYVINYLALCOHOLS ON THE THERMOSTABILITY OF LIPASE FROM CANDIDA-RUGOSA

Lipase from Candida rugosa was stabilized against thermal inactivation in the presence of polyvinylalcohols (PVA) of different molecular wei ghts. The apparent rate constant of the lipase inactivation, k(d), at 49 degrees C is 0.049/min and a 0.022/min in the absence and in the pr esence of PVA (mol wt 22,000), respectively. The improvement of the li pase thermostability by adding PVA was confirmed by differential scann ing calorimetry. The presence of PVA had also an effect on the hydroly tic activity of the enzyme. Furthermore, lipase was modified by covale nt linkage to PVA by means of an original procedure. With respect to t he native enzyme, the modified lipase has a slightly lower specific ac tivity, but it is more stable against heat denaturation (k(d) 0.032/mi n at 49 degrees C).