Dramatic hyperactivation of lipase of Thermomyces lanuginosa by a cationic surfactant: Fixation of the hyperactivated form by adsorption on sulfopropyl-sepharose

Abstract

Soluble lipase from Thermomyces lanuginosa (TLL) was dramatically hyper-activated by a cationic surfactant, cetyltrimethylammonium bromide (CTAB). The greatest hyperactivation (above 340-fold) was observed with 0.005% CTAB. In addition to that, very high hyperactivation was also observed with much higher concentrations of surfactant (100-fold in the presence of 0.3% CTAB). Without surfactant or with very low surfactant concentrations, TLL was not adsorbed to the cationic exchangers. However, in the presence of high concentrations of surfactant (0.3%), the lipase was completely and strongly adsorbed on sulfopropyl-sepharose. The adsorbed enzyme remained hyperactivated (80-fold more active than the soluble enzyme) after elimination of the excess of surfactant. Complete desorption of the hyperactivated TLL from the cationic exchanger is only achieved at 2 M NaCl. The same level of hyperactivation was observed for the hydrolysis of a large substrate: fish oil. The release of EPA (eicosapentaenoic acid) was 80-fold more rapid with hyperactivated TLL derivatives than with TLL very mildly immobilized on CNBr activated agarose. Hyperactivated derivatives were very stable at 25 °C and 37 °C. Full activity was preserved after 1 week.