Supercooled water as medium for enzyme reactions at subzero temperatures.

A water-in-oil emulsion technique was employed to investigate enzyme-catalyzed reactions at sub-zero temperatures in the supercooled liquid state. The results obtained with a monooxygenase (bacterial cytochrome P-450) clearly indicate the potentialities as well as the technical problems of the procedure which might be successfully used to investigate enzyme systems sensitive to cosolvents.