Cross-linked enzyme aggregates with enhanced activity: application to lipases

Seven commercially available microbial lipases were immobilised as their cross-linked enzyme aggregates (CLEAs). Preparations with enhanced activity were obtained by a judicious choice of the precipitant [(NH₄)₂SO₄, 1,2-dimethoxyethane or acetone] and by adding either a crown ether or surfactant, depending on the source of the enzyme. Thus, precipitation of the lipases from Thermomyces lanuginosus and Rhizomucor miehei with (NH₄)₂SO₄ in the presence of SDS, followed by cross-linking with glutaraldehyde, afforded CLEAs with three and two times, respectively, the hydrolytic activity of the native enzymes. Preparations with up to ten times enhanced activity in organic medium were similarly prepared.