15N-isotope and double isotope fractionation studies of the mechanism of 3-methylaspartase: concerted elimination of ammonia from (2S,3S)-3-methylaspartic acid

Abstract

The mechanism of the L-threo-3-methylaspartate ammonia-lyase reaction has been investigated using double isotope (2H/1H, 15N/14N) fractionation techniques; the physiological substrate is deaminated via a concerted mechanism in which Cβ–H and Cα–N bond cleavage occur in the same transition state.