ISOLATION AND COMPOSITION OF PENTOSE NUCLEIC ACIDS 403 



TABLE IX 

 Nucleotide Composition of PNA from Microorganisms 



" See page 395. 



The only PNA isolated from a bacterial species whose nucleotide com- 

 position has so far been determined is that of M ycobacterium phlei.^^ The 

 composition of PNA of Serratia marcescens'^ and of Escherichia coli,^^ and 

 of a nucleoprotein of C. perfringens^^ were determined without prior isola- 

 tion of the nucleic acids. The results of the analyses are shown in Table IX. 



5. PNA FROM Plant Viruses 



The composition of a large number of plant virus PNA preparations has 

 recently been determined by Knight and his collaborators'^"''^ and by 

 Markham and Smith.'*^ The results are of particular interest since in the 

 case of plant viruses we can accept them as describing the composition of 

 native virus PNA without reservations regarding degradation or fraction- 

 ation during isolation. The purity of the virus preparations can be ascer- 

 tained by physical methods, and the nucleotide composition of the isolated 

 PNA was found to agree closely with that of the virus, determined without 

 prior isolation of PNA. The results of these determinations are presented 



" D. Elson and E. Chargaff, Nature 173, 1037 (1954). 



" R. W. Dorner and C. A. Knight, J. Biol. Chem. 205, 959 (1953). 



" F. L. Black and C. A. Knight, J. Biol. Chem. 202, 51 (1953). 



