Mutagenic Alkylating Agents 



307 



The negatively charged mustard, chlorambucil, reacts 

 readily with the sperm heads (Fig. 5) presumably because 

 unlike the nucleoproteins it does not carry a negative charge 

 which repels the mustard. The apparent paradox of a highly 

 mutagenic mustard which does not react with DNA has thus 

 been eliminated. 



Reaction with RNA 



RNA obtained by the method of Kay, Simmons and 

 Bounce (1953) from rat liver was reacted with the phenyl- 

 alanine mustard. The course of the reaction was followed on 



PHENYLALANINE 



MUSTARD 



ONLY 



, jr 0-l57o SOLUTION 



OF RNA. 



TEMP. 37'C. 



HEATED 

 TO 90'C 

 FOR 20 MIN. 



400 



200 



TIME (miN.) 



Fig. 6. Rate of acid formation when • 1 % phenyl- 

 alanine mustard reacts with RNA. 







the automatic titrator (Fig. 6) and the reduction in acid 

 production shows that as with DNA there is very extensive 

 reaction with phosphate groups. But the esters formed are 

 stable and no appreciable acidity was produced on heating. 

 Since reaction with the primary phosphate groups would give 



