ii6 



E. S. CANELLAKIS AND EDWARD HERBERT 



S-RNA separate into three well-defined columns and (c) each component 

 contains its own RNA and ribonucleotide incorporating enzyme. We 

 believe that the exact type of physical relationship that exists between 

 these fractions will be best elucidated by detailed enzymatic studies which 



S-RNA/3 

 n = 40 



60% 



H.J^ 



Nl 



S-RNAy 

 n=34 



237o 



24% 



•N. 



N. 



NJ 

 L. _in 



51% 



16% 



IS, -4 



N 



14%, 



6 X U 



N. 



\. 



< 10% 



n = (7AMP+ 6UMP+ I3GMP+ l3CMP-t- l\//UMP) 



16AMP+5UMP + II GMP+ II CMP+li|;UMP) = n 



Fig. 4. Schematic presentation of the variety of S-RNA molecules present 

 in S-RNA-/S and S-RNA-y. The column of figures on the left and right correspond 

 to the ribonucleotide content and per cent composition of S-RNA-/3 and S-RNA-y 

 respectively. 



are at present under way. Because of the experimental simplicity involved 

 in isolating the ^- and y- fractions, our work has been largely limited to a 

 study of the properties of these two fractions. 



2. Analytical data on S-RNA-^ and -7 



Analytical studies on S-RNA-^ as well as S-RNA-y have shown that 

 they can be grossly distinguished as four molecular species differentiated 

 by their end-groups (Fig. 4). All four molecular species of both S-RNA-/S 

 and -y start with guanylic acid, that is, upon alkaline hydrolysis guanosine 



