THE DENATURATION OF TOBACCO MOSAIC VIRUS AT HIGH PRESSURES

Abstract

Tobacco mosaic virus nucleoprotein ( 14), in common with many proteins, can be denatured by various means.A neutral solution of the virus heated to about 70" will lose its infectivity rapidly and gradually become insoluble in dilute salt solutions.Whether this process is studied by infectivity analyses, as was done by Price (13), or by chemical means, as was done by Lauffer and Price (lo), it can be shown to follow the course of a first order reaction.If the virus solvent is made alkaline to a pH value of 10.5 or 11, this reaction will proceed at an appreciable rate even at room temperature.When the virus is dissolved in strong solutions of urea, gradual changes in the physical and chemical properties of the protein, accompanied by a loss of infectivity, result.As reported by Stanley and Lauffer (15) and confirmed by more recent studies,' this reaction is also of the first order.In all of these processes, there is complete disintegration of the virus particles, resulting in the liberation of nucleic acid.In 1914, Bridgman (4) observed that when egg white is subjected to pressures between 5000 and 7000 atmospheres for half an hour, "it becomes coagulated, presenting an appearance much like that of a hard boiled egg."Bridgman and Conant (5) later showed that carboxyhemoglobin could be coagulated by subjecting it to pressures of 9000 atmospheres for varying periods of time.More recently, Dow and his associates have investigated the pressure denaturation of hemoglobin (6), of insulin (7), and of pepsin and rennin (12).In these studies it was shown that the amount of coagulation of the proteins or the changes in biological activity 1 Lauffer, M. A., unpublished results.