DISINTEGRATION OF VIRUSES 



31 







50 



100 150 



Time in minutes 



200 



250 



FIGURE 2? - LOG CONCEJITRATION OP TOBACCO MOSAIC VIRUS PROTEIN PLOTTED 

 AS A FUNCTION OF TIME OF HEATING AT 69.8° C . in _M_ PHOSPHATE BUFFER AT 

 pH 7. (M.A.Lauffer and W.C. Price, J. Biol. 10 Chem. I33, 1(1940; ) 



Here is plotted the natural logarithm of the concentration of tobacco 

 mosaic virus remaining in solution against the time in minutes of heating at 

 about 70° C. It can be observed that the data fall reasonably well upon a 

 straight line. This type of concentration-time relationship is that character- 

 istic of reactions of the first order. A first order reaction is one in which 

 the rate of decrease of concentration of the reactant is proportional at every 

 Instant to the concentration of the reactant present at that instant. This fact 

 can be expressed most eloquently by the simple differential equation 



where Wj is the virus concentration and t 

 ion (1) becomes 



(1) 



the time. Upon integration, equat- 



logg IV] = loge [VJ -^t 



(2) 



and it is in this form that a straight line can be obtained upon plotting. In 

 both of these equations, the constant k is the specific reaction velocity for 

 the reaction under study. It can be defined as the rate of the reaction at the 

 instant that the concentration of the reactant is unity. H'Tom the integrated 

 form of the equation, it is obvious that the constant k is simply the slope 

 of the line obtained when the natural log of concentration is plotted against 

 time . 



There are several things worth knowing about the kinetics of the denatur- 

 ation of any protein. First of all, one should decide with certainty whether 

 or not the process is really a reaction of the first order, it is evident from 

 a consideration of the data in Kiguxe 25 that there is a certain amount of error 



