Michael addition of thiols with 4-methyleneglutamic acid: Preparation of adducts, their properties and presence in peanuts

The thioethers, S-(4-amino-2,4-dicarboxybutyl)cysteamine, S-(4-amino-2,4-dicarboxybutyl)cysteine and S-(4-amino-2,4-dicarboxybutyl)glutathione, were synthesized by a Michael addition between 4-methyleneglutamic acid and the respective thiol. In dilute aqueous solution, the reactions exhibit second order kinetics; glutathione reacts much slower than cysteine or cysteamine. The adducts were characterized chromatographically, electrophoretically, and by their infra-red and nuclear magnetic resonance spectra. None of these thioethers was detected in peanut plants ( Arachis hypogaea L.), even though large amounts of 4-methyleneglutamic acid, its amide, and glutathione are synthesized during peanut germination.