141 



-9 -q 



27 x 10 M. In comparison to ADGG-BSA (K = 127 x 10 M) 



the ADGG-Con A conjugate is a more potent inhibitor of RNA 

 polymerase II. No inhibition by Con A alone was observed 

 nor was the reaction affected by the presence of the Con A 

 specific sugar D-glucose. This indicates that the observed 

 inhibition is a distinct function of the a-amanitin portion of 

 the conjugate and not due to interaction of the Con A with the 

 enzyme or some component of the reaction mixture. 



The procedures developed for the conjugation of C- 

 hippuric acid and H-DM-ADGG to Con A have provided a means 

 for obtaining specific conjugates of Con A and a-amanitin 

 that retain the biological activities of both components 

 of the conjugate. The binding of the Con A portion of the 

 ADGG-Con A conjugate to a cell receptor should result in a 

 specific cytotoxicity for that cell if the Con A receptors 

 are able to facilitate entry of the conjugate to the cell. 

 The interaction of ADGG-Con A conjugates with cultured CHO 

 cells was examined to first establish whether the Con A 

 receptor could facilitate entry of the amanitin portion of 

 the conjugate into the cell and secondly, determine whether 

 any such entry resulted in greater toxicity than for free 

 a-amanitin following exposure of the cells to equivalent 

 concentrations of free and conjugated a-amanitin. 



Two CHO lines, H-7 and a Con A resistant mutant H-7Wcr, 



125 

 were both found to bind equivalent quantities of I- 



Con A following a single 15 minute exposure at 22°C (Figure 



23). The H-7Wcr line is resistant to Con A cytotoxicity at 



