Discriminating between dispersion and lyoprotection effects in biocatalysis in organic media

The increment of activity and solubility in 1,4-dioxane of lipase B from Candida antarctica, lipase from Pseudomonas cepacia, and subtilisin, were investigated as a function of the methoxypoly(ethylene glycol)-protein (PEG-protein) ratio employed during lyophilization. Both activity and solubility markedly increased as the PEG-protein ratio was increased. The increment of activity at low PEG-protein ratios, however, was much higher than that of solubility. These data suggest that the PEG-induced activation effect is due mainly to a lyoprotection effect rather than to relaxation of diffusional limitations.