IN-SITU HYDRATION OF ENZYMES IN NONPOLAR ORGANIC MEDIA CAN INCREASE THE CATALYTIC RATE

A comparison of the initial catalytic rate was made between enzyme equilibrated with water through the vapour phase and enzyme equilibrated whilst suspended in n-hexane at fixed water activities, a(w). The rate of enzymic catalysis below a(w) = 0.58 is essentially the same for the two equilibrated systems. However at water activities greater than 0.58 it was found that enzyme hydrated in the presence of solvent showed a significant and reproducible rate enhancement. We have shown that this enhancement is not because of differences in the number of adsorbed water molecules. The possibility that it arises from either variations in the distribution of active conformations or microscopic variations in the protein powder is discussed.