Studies on the Interaction between Regulatory Enzymes and Effectors

In order to elucidate the chemical basis of interaction between regulatory enzymes and effectors, various structural analogues of adenosine 5'-monophosphate were investigated for the activating effect on the biodegradative threonine deaminase of Escherichia coli. The mode of activation by each compound was analyzed kinetically in terms of the maximal activation effect and the concentration which gave a half-maximal activation. The results with 38 compounds indicated that the base part of AMP was relatively nonspecific with regard to the maximal activation effect, but played a significant role in the binding; especially substitutions at the 6-amino group appeared to decrease the affinity. The ribose moiety contributed both to the binding and activation; especially the presence of a hydroxyl group at position 2‘ was important. The monophosphate group at position 5‘ was required both for the activation and binding.