Biocatalysis in low-water media: understanding effects of reaction conditions

The key role played by counter-ions with enzymes in low-water systems has b ecome better appreciated with, for example, large effects on enantioselecti vity. In low-dielectric media, counter-ions will associate strongly with ch arges in the protein or its substrates, Studies of temperature dependence h ave shown that hard-to-model entropies have a significant effect on behavio ur, including enantioselectivity. Evidence has been presented that the supr amolecular organisation of enzyme molecules can have important effects on b ehaviour, for example collapse of microstructure in cross-linked crystals.