Examining structure–activity correlations of some high activity enzyme preparations for low water media

A first study of the comparison of structures of enzymes (by FT-IR and CD) in different high activity (in low water media) preparations is reported. Using chymotrypsin and subtilisin as models, we have studied various factors that distinguish enzyme precipitated and rinsed with propanol (EPRP), crosslinked enzyme aggregates (CLEA), protein coated microcrystals (PCMC) and crosslinked protein coated microcrystals (CLPCMC). The suspensions in organic media were assayed for catalytic activity, and structures were probed by FT-IR and CD measurements. CD studies of enzyme suspensions were possible by using a rotating cell accessory. There was a generally good correlation between higher catalytic activity and retention of native structures. Activity and retention of native structure was always higher if aqueous enzyme solution was added to propanol rather than vice versa in the precipitation step of these preparations. The work identifies factors which may lead to better biocatalyst designs for low water media.

► Adding aqueous enzyme solution to propanol gives better activity than vice versa. ► Rotating cell accessory enables CD spectra of enzyme suspensions in organic media. ► FT-IR and CD agree closely on extent of structural change in different formulations. ► Retaining structure close to native is an important reason for high activity.