title: Partial 13C isotopic enrichment of nucleoside monophosphates: useful reporters for NMR structural studies.
abstract: Analysis of the 13C isotopic labeling patterns of nucleoside monophosphates (NMPs) extracted from Escherichia coli grown in a mixture of C-1 and C-2 glucose is presented. By comparing our results to previous observations on amino acids grown in similar media, we have been able to rationalize the labeling pattern based on the well-known biochemistry of nucleotide biosynthesis. Except for a few notable absences of label (C4 in purines and C3' in ribose) and one highly enriched site (C1' in ribose), most carbons are randomly enriched at a low level (an average of 13%). These sparsely labeled NMPs give less complex NMR spectra than their fully isotopically labeled analogs due to the elimination of most 13C-13C scalar couplings. The spectral simplicity is particularly advantageous when working in ordered systems, as illustrated with guanosine diphosphate (GDP) bound to ADP ribosylation factor 1 (ARF1) aligned in a liquid crystalline medium. In this system, the absence of scalar couplings and additional long-range dipolar couplings significantly enhances signal to noise and resolution.
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602-4712, USA.
authors.forename: Anita I
authors.initials: AI
authors.lastname: Kishore
authors.forename: Michael R
authors.initials: MR
authors.lastname: Mayer
authors.forename: James H
authors.initials: JH
authors.lastname: Prestegard
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000737:chemistry / Q000378:metabolism; D002247:Carbon Isotopes; D004926:Escherichia coli / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009711:Nucleotides / Q000096:biosynthesis / Q000737:chemistry*; D010427:Pentose Phosphate Pathway; D011687:Purines / Q000096:biosynthesis / Q000737:chemistry; D011743:Pyrimidines / Q000096:biosynthesis / Q000737:chemistry; D014542:Uridine Monophosphate / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D009711:Nucleotides; D011687:Purines; D011743:Pyrimidines; D006153:Guanosine Diphosphate; D014542:Uridine Monophosphate; D020823:ADP-Ribosylation Factor 1