Abstract
Magic-angle single and double cross-polarization 13C and 15N NMR spectra have been obtained of lyophilized soybean cotyledons cultured on media containing, as the only nitrogen source, [4-13C, amide-15N]asparagine. Single cross-polarization NMR shows directly and unambiguously that both labels from asparagine are incorporated extensively and nonrandomly into protein by the developing cotyledon during a 2-week period. A stable-isotope double label tags a chemical bond. The metabolic fate of the asparagine double label was followed by double cross-polarization NMR using the latter's sensitivity to the dipolar coupling between directly bonded 13C and 15N. These experiments show that in culture the direct incorporation of asparagine (with no scrambling of label) accounts for about half of all asparagine residues in soybean protein. This conclusion implies the operation of a regulatory apparatus in soybeans for both direct utilization and degradation of asparagine in protein synthesis.
Keywords: double cross-polarization, 15N NMR, magic-angle spinning, stable-isotope chemical bond labeling
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Lapidot A., Irving C. S. Dynamic structure of whole cells probed by nuclear Overhauser enhanced nitrogen-15 nuclear magnetic resonance spectroscopy. Proc Natl Acad Sci U S A. 1977 May;74(5):1988–1992. doi: 10.1073/pnas.74.5.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schaefer J., Kier L. D., Stejskal E. O. Characterization of photorespiration in intact leaves using carbon dioxide labeling. Plant Physiol. 1980 Feb;65(2):254–259. doi: 10.1104/pp.65.2.254. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schaefer J., Stejskal E. O., McKay R. A. Cross-polarization NMR of N-15 labeled soybeans. Biochem Biophys Res Commun. 1979 May 14;88(1):274–280. doi: 10.1016/0006-291x(79)91726-1. [DOI] [PubMed] [Google Scholar]
- Shulman R. G., Brown T. R., Ugurbil K., Ogawa S., Cohen S. M., den Hollander J. A. Cellular applications of 31P and 13C nuclear magnetic resonance. Science. 1979 Jul 13;205(4402):160–166. doi: 10.1126/science.36664. [DOI] [PubMed] [Google Scholar]