ENZYME-REACTIONS IN MICROSTRUCTURED MEDIA - SUBTILISIN CATALYSIS IN ALKYL GLUCOPYRANOSIDES AGGREGATES

In order to understand the effect of the structures of the surrounding medium on biocatalytic reactions, hydrolytic catalysis by subtilisin Carlsberg in a ternary system containing octyl beta-D-glucopyranoside (beta-OG), water, and octanol (OcOH) was studied, with special referen ce to the enzyme reactivity and the morphology of the surfactant aggre gates. First, the effect of beta-OG and other alkyl D-glucopyranosides (AG) on the subtilisin reaction was studied in the surfactant/water b inary system; all four surfactants tested were found to inhibit the su btilisin catalysis. Then, a detailed phase diagram of beta-OG/water/oc tanol was determined and several liquid crystalline phases were found. When the subtilisin reactions were measured in several compositions i n the phase diagram, the maximum of the apparent rate was observed in reversed micells as well as in the reversed hexagonal phase at a certa in [water]/[surfactant] ratio (w(o)). The apparent optimal w(o) was ca lculated to be around 5-6. These results were compared with the result s in another ternary system of Aerosol OT/water/isooctane.