Oxidation of (horse) hemoglobin by copper: an intermediate detected by electron spin resonance.
The oxidation of horse hemoglobin by Cu(II) has been followed by the changes in the electron spin resonance spectra of copper. By stopped-flow and freeze-quenching techniques, it is shown that the second-order rate constant for the binding of Cu(II) to hemoglobin is greater than 5 X 10(5) mol-1 s-1 and the apparent first-order rate for the reduction of Cu(II) to Cu(I) is 0.051 s-1. It is also shown that the binding of Cu(II) to hemoglobin is followed by an alteration of the Cu(II) spectrum, decreasing the g values. This process has an apparent rate constant of 17 s-1 and presumably involves a conformational change in the region of the copper binding site. It is also shown that this conformational change is apparently necessary for Cu(II) to oxidize hemoglobin.
D000818:Animals; D003300:Copper; D004578:Electron Spin Resonance Spectroscopy; D006454:Hemoglobins; D006736:Horses; D007700:Kinetics; D010084:Oxidation-Reduction
D006454:Hemoglobins; D003300:Copper