Open Access15N and 13C NMR Determination of Methionine Metabolism in Developing Soybean Cotyledons
Author(s) -
George T. Coker,
Joel R. Garbow,
Jacob Schaefer
Publication year - 1987
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.83.3.698
Subject(s) - methionine , transmethylation , glycine , methionine synthase , biochemistry , metabolism , chemistry , amino acid , biology
The metabolism of d- and l-methionine by immature cotyledons of soybean (Glycine max, L. cv Elf) grown in culture has been investigated using solid-state (13)C and (15)N nuclear magnetic resonance. d-Methionine is taken up by the cotyledons and converted to an amide, most likely by N-malonylation. About 16% of the l-methionine taken up is incorporated intact into protein, and 25% remains as soluble methionine. Almost two-thirds of the l-methionine that enters the cotyledons is degraded. The largest percentage of this is used in transmethylation of the carboxyl groups of pectin. Methionine is not extensively converted to polyamines. We attribute the stimulation of growth of the cotyledons by exogenous methionine to the bypassing of a rate-limiting methyl-transfer step in the synthesis of methionine itself, and subsequently of pectins and proteins.