Nobuyoshi Esaki

Preparation of Isotopicafly-Labeled Amino Acids with L-Methionine γ-Lyase

L-Methionine γ-lyase catalyzes the exchange of α- and β-hydrogens of L-methionine and S-methyl-L-cysteine with deuterium or tritium as solvents. The rate of α-hydrogen exchange with deuterium was about forty times faster than that of the elimination reactions. The deuterium and tritium were exchanged also with the α- and β-hydrogens of the straight-chain amino acids which do not undergo the elimination: L-alanine, L-α-aminobutyrate, L-norvaline, and L-norleucine. These enzymatic hydrogen-exchange reactions facilitate specific labeling of the L-amino acids with deuterium and tritium.