130 THE PHYSICS OF VIRUSES 



(lueiit strong attraction. Once attraction has occurred and the 

 virus and bacterium are in contact, an irreversible enzymatic 

 process takes place which is temperature sensitive, and inhibited 

 by Zn"'""'" in the case of E. coli. 



Some interesting deductions can be made from this story. 

 In the first place, the ionic binding is so strong that the virus 

 and bacterium should be tightly locked together. This being 

 so, the fact that the enzymatic process is 90%, or more, effective 

 at 37° C means that a large part of the bacterial surface must be 

 substrate. Garen and Puck also made the observation that 

 4 X 10^ atoms of zinc are absorbed per cell of E. coli in order to 

 block the enzymatic step. Assmning that these are all on the 

 surface of the E. coli and that the bacterium is a cylinder l/>t in 

 diameter by 2/x long, the total surface available for distribution is 

 roughly 6 X 10^ A^. Since this is matched on the virus surface 

 by an identical distribution, the specific groupings must occupy 

 an area of 15 A^. This number is probably low because it is 

 based on the assumption that all the zinc goes in the surface of 

 the bacterium. Nevertheless, the indication is that there exists a 

 small charge groui)ing that is similar to that on the bacterium. 

 Associated with this is an enzymatic type of surface. 



These powerful methods of study are just in their early phases. 

 Quite detailed knowledge of the virus and bacterial surfaces can 

 be expected to result. 



Polypeptide Attachment 



Some very remarkable work in which the combination of 

 lysine polypeptides with tobacco mosaic virus has been studied 

 is due to Stahmann, Graf, Patterson, Walker, and Watson (1951) 

 and to Burger and Stahmann (1951). In the first of these papers, 

 the formation of synthetic polypeptides from E-carbobenzoxy- 

 a carboxy-L-lysine anhydride is described. The chain length 

 can be varied and measured by finding the proportion of termi- 

 nal Qj-amino nitrogen. An elementary analysis of one such 

 polypeptide gave Ci,366Hi,754Ni940294, which has a molecular 

 weight of roughly 25,000. 



They show that such a i)olypeptide can cause the inhibition 



