THE SYNTHESIS OF PROTEINS 



31 



autocatalytic equation dv/dt = KV{Ve — V) when Ve = total concen- 

 tration at end of reaction and V = concentration® of virus at time t. 



The explanation of the next step depends on whether or not the varia- 

 tion in the number of virus molecules formed varies with the number 

 of molecules with which the bacteria is infected. The direct experimental 

 results show that it does, but Delbriick and Luria suggest that this is due 

 to secondary reactions. 



If it be assumed that the number of molecules produced does vary 

 with the size of the infection, then it must be assumed that the time re- 

 quired for liberation of the virus depends to some extent on the bacteria 

 cell and not entirely on the number of virus molecules present. There is 

 some indication of this, since changing the temperature changes this 

 time interval in the same way as it does the growth rate of the bacteria. 



We may assume that virus is liberated after a definite time has elapsed 

 and that this time is determined both by the state of the bacteria cell 

 and by the nature of the virus, but not by the number of molecules of 

 virus. The theory of autocatalytic reaction applied to these conditions 

 predicts that the number of molecules produced in the interval will in- 

 crease more slowly than does the original number. Fig. 2 shows a series 



.4 .8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0 44 4.8 



T 



Figure 2. Effect of initial concentration of the end product on an autocatalytic reaction. 



^ It may be recalled in this connection that most enzyme reactions deviate from simple 

 theory in that the velocity does not change in the expected way with either the enzyme 

 or substrate concentration. In the case of the autocatalytic formation of pepsin from 

 pepsinogen, for instance, increasing the concentration has much less effect on the 

 velocity than predicted by the equation given above (Herriott, 1938). 



