The Denaturation of Proteins by Sound Waves of Audible Frequencies

When egg albumin in aqueous solution at the isoelectric point is subjected to the action of intense sound waves of audible frequency, a coagulum is produced (1). A previous investigation (2) indicated that such sound-denatured’ albumin is immunologically similar to denatured albumin prepared in other ways; e.g., by heat in acid, alkdme, or neutral solution, by alcohol, or by acid or alkali. Wu and Liu (3), making use of ultrasonic waves of much higher frequency than any employed by us, were able to coagulate albumin. However, when CO2 or H&S was substituted for air in the solutions or when no gas at all was present, they observed no change with ultrasonic treatment. This contrasts with their observation that the reaction proceeds normally in the presence of pure 02 or HZ. Although the results of our previous studies indicate that the end-product of sonic denaturation is probably the same as that produced by heating and therefore may be the result of a thermal type of activation, they leave unexplained the mechanism through which mechanical vibrations may energize the reaction. The peculiar relationship of the reaction toward certain gases reported by Wu and Liu has not clarified the mechanism for either range of frequency. We have therefore undertaken a further study of the sonic denaturation of certain proteins, first, to compare the end-products of the reactions with those produced by other means with