NMR spectroscopic identification of a hexacyanochromate(III) binding site on Pseudomonas azurin

Publisher Website
Google Scholar
Abstract
The interaction between oxidized P. aeruginosa azurin and the anion Fe(CN)63- and between reduced azurin and Cr(CN)63- was studied. At low ionic strenghts, stoichiometric binding of 1 Fe(CN)63- ion to the oxidized protein was observed. In the high-resolution PMR spectra of the reduced protein, specific broadening of the assigned residues was observed upon titration with the redox-inert Cr(CN)63- ion. Analysis of this paramagnetic spectral broadening in terms of the 3-dimensional structure of the protein led to the proposal that the binding site of the anions lies approximately midway between lysine residues 85 and 92. Evidence in support of this conclusion was provided by parallel studies on Alcaligenes faecalis azurin, which lacks these lysine residues. A similar site on the surface of Pseudomonas azurin was recently identified by affinity labeling with Cr2+ as an electron-transfer locus. Evidently, this region on the protein surface may also be employed by anionic electron-transfer agents.
Keywords

This publication has 1 reference indexed in Scilit: