
%0 Journal Article
%A Trewhella, J 
%A Appleby, CA 
%A Wright, PE 
%T <sup>1</sup>H N.M.R Studies of High-Spin Complexes of Soybean Leghemoglobin. Interactions Between the Distal Histidine and Acetate, Formate and Fluoride Ligands
%J Australian Journal of Chemistry
%D 1986/02/01
%V 39
%N 2
%P 317-324
%K 
%R https://doi.org/10.1071/CH9860317
%U https://www.publish.csiro.au/paper/CH9860317 
%X High-resolution 1H n.m.r . spectra have been measured for the acetate, formate and fluoride complexes of ferric soybean leghaemoglobin a. The chemical shifts of the resolved ow-field haem resonances are very sensitive to pH, reflecting titration of a group, assigned as the distal histidine, with pKa 7.1, 7.3 and 6.2 for the acetate, formate and fluoride complexes respectively. The magnitude of the pH-induced resonance shifts indicates direct interaction between the distal histidine and the axial ligand . The hyperfine shifted resonances of ferrous deoxyleghaemoglobin, in which no sixth ligand is expected, are insensitive to pH over the range pH 5.5-9.3. Evidence for conformational mobility of the distal histidine is presented. 
