This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (23) Citing Articles via Google Scholar Google Scholar Articles by Skokut, T. A. Articles by McKay, R. A. Search for Related Content PubMed PubMed Citation Articles by Skokut, T. A. Articles by McKay, R. A. Agricola Articles by Skokut, T. A. Articles by McKay, R. A.

Articles

[¹⁵N]NMR Determination of Asparagine and Glutamine Nitrogen Utilization for Synthesis of Storage Protein in Developing Cotyledons of Soybean in Culture

Department of Biology, Washington University, St. Louis, Missouri 63130, Physical Sciences Center, Monsanto Co., St. Louis, Missouri 63166

Solid-state [¹⁵N]NMR was used to measure the use of the amide and amino nitrogens of glutamine and asparagine for synthesis of storage protein in cotyledons of soybean (Glycine max L. cv. Elf) in culture. No major discrimination in the incorporation of the amide or amino nitrogens of glutamine into protein is apparent, but the same nitrogens of asparagine are used with a degree of specificity. During the first seven days in culture with asparagine as the sole nitrogen source, the amino nitrogen donates approximately twice as much nitrogen to protein as does the amide nitrogen. The use of the amide nitrogen increases with longer periods of culture. The reduced use of the amide nitrogen was confirmed by its early appearance as ammonium in the culture medium. The amide nitrogen of asparagine was found at all times to be an essential precursor for protein because of its appearance in protein in residues whose nitrogens were not supplied by the amino nitrogen. In addition, methionine sulfoximine inhibited growth completely on asparagine, indicating that some ammonium assimilation is essential for storage protein synthesis. These results indicate that in a developing cotyledon, a transaminase reaction is of major importance in the utilization of asparagine for synthesis of storage protein and that, at least in the early stages of cotyledon development, reduced activities of ammonium-assimilating enzymes in the cotyledon tissue or in other tissues of the seed or pod may be a limiting factor in the use of asparagine-amide nitrogen.

This article has been cited by other articles:

				L. Cegelski and J. Schaefer Glycine Metabolism in Intact Leaves by in Vivo 13C and 15N Labeling J. Biol. Chem., November 25, 2005; 280(47): 39238 - 39245. [Abstract] [Full Text] [PDF]