Ethylene biosynthesis. 7. Secondary isotope effects

In a continuing investigation of the mechanism of the biosynthesis of ethylene, the plant ripening hormone, from 1-amino-cyclopropanecarboxylic acid, the study of isotope effects was undertaken in order to provide insight into the rates of various bond-breaking steps. While the applicability of the concept of rate-limiting step to enzymatic reactions has been questioned and redefined (and there is little doubt an ethylene-forming enzyme exists), such studies were expected to elucidate some mechanistic detail as well as measure the validity of a model for ethylene biosynthesis.