title: Carbon-13 NMR studies on [4-13C] uracil labelled E. coli transfer RNA1(Val1).
abstract: In this paper we describe carbon-13 nuclear magnetic resonance results on 13C-enriched purified transfer RNAI(VAL) from from E. coli SO-187, a uracil requiring auxotroph. The organism was grown on uracil 90% 13C-enriched at the carbonyl C4 position. Transfer RNAI(Val) was purified from bulk tRNA by sequential chromatography on columns of BD cellulose, DEAE-Sephadex A-50 and reverse gradient sepharose 4B. Dihydrouridine, 4-thiouridine, and uridine 5-oxyacetic acid located at discrete positions in the polymer backbone were tentatively assigned in the highly resolved 25 MHz 13C-spectra. Chemical shift versus temperature plots reveal differential thermal perturbation of the ordered solution structure, evident in the large dispersion (ca 3-4 ppm) of the uridine C4 resonances. Over the range 26-68 degrees C, V in the anticodon displays the largest downfield shift. Whereas several uridine residues rapidly shift downfield between 50-68 degrees, one moves upfield beginning at 37 degrees. The results are qualitatively compared with proton NMR analysis of the three dimensional structure.
mesh_terms: D002247:Carbon Isotopes; D004926:Escherichia coli / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D009690:Nucleic Acid Conformation; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D013696:Temperature; D014633:Valine / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D012346:RNA, Transfer, Amino Acyl; D014633:Valine