On the ‘heat coagulation’ of proteins

ON heating soltutions of many proteins, as temperature rises, an irreversible change of state occurs-so-called "heat-coagulation." Similarly, in the case of most proteins endowed with active physiological properties (e.g. ferments, toxins, lysins, opsonins, complements, etc.), at or about a particular temperature these properties are destroyed. Up to the present it has been the almost universal practice to regard the temperature at which change of state or loss of activity occurs, as if it were a physical constant characteristic of the particular protein, this temperature being subject to small variations according to the conditions of experiment. This may however be an entirely misleading way of regarding the matter and the well-known fact that the destruction of active properties, or precipitation as the case may be, does not occur instantaneously suggests a time process in which heat merely plays the subsidiary part of accelerator. This view of the coagulation of proteins was indeed advanced by Duclau x (1893) and has since been established by Famulener and Madsen (1908) for the destruction of the active properties in solutions of three antigens, vibriolysin, tetanolysin and goats'-serum-haemolysin, and by Madsen and Streng (1909) for agglutinins. We have occupied ourselves in the first instance with an investigation of the laws governing the precipitation of solutions of pure proteins because such a process lends itself more easily to accurate quantitative methods.