Biosynthesis of 1-aminocyclopropanecarboxylic acid: Steric course of the reaction at the C-4 position

Summary Under the action of the appropriate synthase from ripe tomatoes a 11 mixture of (3S, 4R)-3,4-²H₂] and (3R, 4S)-3,4-²H₂]-(2S)-adenosylmethionine is transformed into a 11 mixture of the two meso forms of ²H₂]-1-aminocyclopropanecarboxylic acid, a result which proves the operation of an inversion mechanism and which is consistent with direct nucleophilic displacement of the leaving group in the substrate.