Metabolism and mode of action 



The apparent ability of 2:4-dichloroanisole to react with sulphydryls 

 suggests that at least a part of the growth inhibition by that compound may be 

 due to this characteristic. And since we have not found auxins to share this 

 quality, it is not very surprising that some workers have not found it to 

 inhibit growth in a manner competitive with auxin (Audus and Shipton, 

 1952; Housley et al., 1954). 



In conclusion, it would seem appropriate at this point to recall the caution 

 given by Audus (1953) that there is no reason to believe a priori that growth 

 inhibitors have a simple action in growth. Substances which we may think 

 of as anti-auxins in the strictest sense may not act as good competitive 

 inhibitors of auxin in many tests, for their ability to carry out side reactions 

 may certainly alter the kinetics of their effects. We feel that the ability of 

 TIBA, coumarin, and 2:4-dichloroanisole to react with sulphydryls may 

 certainly contribute to their growth responses, though it is certainly not 

 entirely responsible for them or iodoacetate would mimic them precisely. 



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