THE INITIATION OF BACTERIOPHAGE INFECTION 



225 



of alteration of the tail appears to be related to the efficiency of the reagent 

 in breaking thiolester bonds. 



TABLE III 



Chemical and Physical Treatments ^VHICH Alter the Structure of T2 



Key to symbols: 



+ Indicates that the treatment is effective. 



Indicates that no visible change occurred. 



? Indicates that although no visible change occurred, there is other evidence that the 

 treatment had some effect. 



Although it is kno-mi that other treatments, such as urea (Cohen, 1947), p-chloro- 

 mercuribenzoate (Puck and Tolmach, 1954), and formaldehyde (Tolmach and Puck, 

 1952) inactivate T2 and presumably alter its structure, no electron micrographs are 

 available. Therefore these results are not tabulated. 



The effects of these reagents also reveal some properties of the phage head 

 protein. The destruction of the head protein by thioglycollate and prolonged 

 peroxide treatment (but not brief peroxide treatment) suggests that one of 

 the factors in maintaining the structure of the head is disulfide bonding. It 

 also appears that the highly organized head structure can be disrupted by 



VOL. II — 15 



