IMPROVEMENT OF ENZYME-ACTIVITY AND STABILITY FOR REVERSE MICELLAR-ENCAPSULATED LIPASES IN THE PRESENCE OF SHORT-CHAIN AND POLAR ALCOHOLS

In this report, we demonstrate that the initial activity of lipases fr om Rhizopus delemar and Candida rugosa encapsulated in Water /AOT/isoo ctane reverse micelles is greatly enhanced when short-chain n-alkanols (<C-5) are present in the medium prior to lipase encapsulation and re duced when long-chain alcohols are present. In addition, enzyme stabil ity for micellar encapsulated lipase was significantly increased when the medium contained both fatty acid and glycerol substrates (esterifi cation reaction). For these cases, the substitution of tetradecane for isooctane as solvent further increased the lipase's half-life from ca . 1 to ca. 3 weeks. An explanation for these results is given which is based on the enhancement of intermicellar attractive interactions and micellar clustering by short-chain and polar alcohols and long-chain oils. Accompanying these changes is a disordering of the structure for the micellar interface and a reduction of the interfacial tension, bo th of which would reduce enzyme-surfactant head group interactions, wh ich is believed to be the main promoter of enzyme inactivation.