232 



A. M. KUZIN 



both after injection of artificially obtained preparations (see Fig. 7) 

 and after injection of purified protein-free extracts from irradiated 

 leaves (see Fig. 8). 



The mechanism of action of the products of oxidation of tyrosine on 



I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 



Days 



Fig. 7. — Weight curves of young mice.* Day of injection of tyrosine oxidation product 



o ■'^' 



OJ 



(/I -^ 

 O -1-J 

 0) 0) 



CD 



a 



i_ 



> 



D 



5 6 7 

 Dcys 



8 9 10 II 



Fig. 8. — Weight curves of young mice after subcutaneous injection of purified extract 

 from irradiated and normal leaves.* Day of injection. 



the cells nucleus is unknown l)ut we thought it probable that it was an 

 interaction between these chemically active substances and DNA. 



The easy condensation of quinones with substances containing amino 

 groups is well known. Quinones condensing with adenosine, guanosine 

 or cytidine groups in DNA could considerably alter the reactivity of 

 the DNA molecule as a whole. If such a reaction took place we could 



