Open AccessA Study of the Thermal Unfolding of Escherichia coli Phenylalanine Transfer RNA by Chemical Modification at Elevated Temperatures
Author(s) -
GODDARD John P.,
LOWDON Margaret
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb12558.x
Subject(s) - cytidine , chemistry , phenylalanine , protein tertiary structure , hydrogen bond , transfer rna , rna , escherichia coli , stereochemistry , protein secondary structure , crystallography , molecule , enzyme , biochemistry , organic chemistry , amino acid , gene
Escherichia coli tRNA Phe was modified by 3 M sodium bisulphite pH 6.0 for 24 h in the temperature range 25 °C (× 5 °C) to 55 °C and in the absence of added magnesium ions. The sites and extents of conversion of cytidines to uridine occurring at each temperature were determined by fingerprinting. The new sites of cytidine modification found at higher reaction temperatures were assumed to arise from breakage of secondary and tertiary structure hydrogen bonds involving cytidine residues. From these data, we conclude that hydrogen bonds within the ‘complex core’ of the tRNA (including the base pairs G‐10 · C‐25, C‐11 · G‐24 and C‐13 · G‐21 within the dihydrouridine stem and the tertiary structure base pair G‐15 · C‐48 melt at a lower temperature than the tertiary structure hydrogen bonds between G‐19 in the dihydrouridine loop and C‐56 in the TΨC loop.