BACTERIOPHAGES 



TABLE VIII 



Gross Chemical Components of Phages 



(per cent by weight) 



Car- 

 Pro- bohy- 

 Phage tein DNA" RNA" drate Lipid Referer 



" DNA = deoxyribonucleic acid. 

 * RNA = ribonucleic acid. 



4. Gross Chemical Components 



The few analyses available on the protein, carbohydrate, 

 lipid, and nucleic acid components of bacteriophages are sum- 

 arized in Table VIIL There seems to be general agreement 

 that the phages analyzed are about half protein and half nucleic 

 acid of the deoxyribose type. The intrinsic lipid and ribo- 

 nucleic acid of phage T2 appears to be very small, if any. On 

 the basis of the radioactivity in the mononucleotide fraction of 

 phage T2 produced from a P^--labeled medium, Volkin and 

 Astrachan (1956c) placed the upper limit of the ribonucleic acid 

 content of this phage at 0.025 per cent and argued that the dis- 

 tribution of radioactivity was such that even this quantity is 

 probably an impurity. 



The protein of phage T2 is physically separable into two 

 kinds (Hershey, 1955). One of these is the coat or "ghost" of 

 the phage particle and the other is a relatively small soluble 

 protein. The latter is probably mixed with the DNA in the 

 phage head for it is injected into the cell, and it is readily lib- 

 erated into the medium following osmotic shock which releases 

 the DNA. The amino acid analyses of these two protein com- 

 ponents are not distinctively different. 



