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Investigation of the base‐pairing structure of the anticodon hairpin from E. coli initiator tRNA by high‐resolution nmr
Author(s) -
Wong K. Lim,
Kearns David R.
Publication year - 1974
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1974.360130212
Subject(s) - chemistry , transfer rna , base pair , stacking , nuclear magnetic resonance spectroscopy , residue (chemistry) , crystallography , resolution (logic) , molecule , stereochemistry , pairing , base (topology) , nuclear magnetic resonance , dna , rna , physics , biochemistry , organic chemistry , mathematical analysis , superconductivity , mathematics , quantum mechanics , artificial intelligence , computer science , gene
The high‐resolution nmr spectrum of the anticodon hairpin from E. coli tRNA fMet has been obtained at a number of different temperatures. The positions of the resonances from interior Watson‐Crick base pairs are well accounted for (within 0.1 ppm) by a semi‐empirical ring current shift theory, but the terminal base pairs are susceptible to the exact orientation of adjacent bases in single‐stranded regions. From a careful examination of the exact way in which resonances disappear at elevated temperatures, we conclude that melting in the nmr experiments occurs when the lifetime of a base pair is reduced to several milliseconds. On the basis of these experiments we are able to assign an nmr T m to each individual base pair and these should be useful in interpreting the melting behavior of the intact molecule. An “extra” resonance is observed at ∼11.3 ppm and, on the basis of its position and temperature sensitivity, it is tentatively assigned to the ring nitrogen proton of a “protected” U residue in the anticodon loop. A strong preference for stacking of a nonbase‐paired A residue on an adjacent GC base pair is observed even at temperatures in excess of 52°C.