302 H. G. BOMAN, I. A. BOMAN 



TABLE I 



Effect of Guanidino Derivatives on the Arginine-Activating Enzyme 



The concentration of the compounds listed under "Addition" were 3 mM, and 

 the [^*C]-arginine concentration was o • 28 mM in all experiments. The concentration 

 of the [^*C]-alga protein hydrolysate was 3-4 /Ltg./ml. in the experiment with 

 streptomycin and 8-4 /xg./ml. in the one with canavanine. Except for the use of an 

 excess of RNA from 3oSq, the assay was carried out as described under Materials 

 and Methods. The activity in c.p.m. is given without correction for self-absorption 

 and geometry. 



2 < 6 e 



mM Canavanine 



Fig. 2. Activity of the arginine-activating enzyme as a function of canavanine 

 concentration. The concentration of [^^C]-arginine was o -28 mM. Enzyme purified 

 from strain 30S0 represented by open circles; from strain 30S0A5 by filled circles. 



