Alternate Substrates and In hi bitors of 1 -Aminocyclopropane-I -carboxylic Acid Synthase

Structural analogs of (-)-S-adenosyl+methionine (SAM), in which the heterocyclic base was modified, were used to initiate studies to elucidate the active site conformation of the enzyme l-aminocyclopropane-I-carboxylic acid (ACC) synthase, which was partially purified from Lycopersicon esculentum (tomato). These potential substrate analogs were screened for activity both as substrates and/or as inhibitors of ACC synthase. In general, ACC synthase was found to have a rather rigid specificity for the structural features of the natural substrate (SAM) in that only the purine base adenosine and adenosine analogs in which the N6 nitrogen was modified were substrates. o 1987 Academic Press. IX.