| Abstract: | The power to survive prolonged exposure to low temperatures is possessed by various enzymes, including those producing hydrolysis of fats, of carbohydrates, and of proteins, those concerned in biochemical oxidations and reductions, the clotting enzymes and that of alcoholic fermentation. The enzymes retained their catalytic power after exposure, either in situ or in solution in vitro, to temperatures varying from a few degrees above 0° C. to the temperature of liquid air (?180° to ?191° C.). The shortest periods of holding, invariably less that one day and usually less than one hour, were at the temperature of liquid air. The longest period of holding was eighty-nine months at a temperature of ?9.4° to ?12.2° C.The activity of certain of these enzymes, including rennin, zymase, and those hydrolyzing fats, carbohydrates, and proteins, has been studied at low temperatures, varying from that of an ice-box to one of ?9° to ?12° C. While the enzymes produced autolytic digestion or acted on artificial media at these temperatures, the velocity of the reaction was always lessened to a considerable degree. |
