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Fluorine‐19 NMR studies of the thermal unfolding of 5‐fluorouracil‐substituted Escherichia coli valine transfer RNA
Author(s) -
Chu Wen-Chy,
Horowitz Jack
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)81408-z
Subject(s) - transfer rna , chemistry , nuclear magnetic resonance spectroscopy , escherichia coli , crystallography , acceptor , denaturation (fissile materials) , stereochemistry , rna , biochemistry , nuclear chemistry , physics , gene , condensed matter physics
19 F NMR spectroscopy was used to monitor the thermal unfolding of E. coli tRNA Val labeled by incorporation of 5‐fluorouracil (FUra). With rising temperatures, resonances in the 19 F NMR spectrum of (FUra)tRNA Val gradually shift towards the central region of the spectrum and merge into a single broad peak above 85°C. FU55 and FU12 are the first to shift, beginning at temperatures below 40°C, which suggests that the initial steps of thermal denaturation of tRNA Val involve disruption of the tertiary interactions between the D‐ and T‐arms. The acceptor stem and the FU64‐G50 wobble base pair in the T‐stem are particularly stable to thermal denaturation. A temperature‐dependent splitting of the 19 F resonance assigned to FU64, at temperatures above 40°C, suggests that the T‐arm of (FUra)tRNA Val exists in two conformations in slow exchange on the NMR time scale.