Magnetic and spectral properties of carp carbonmonoxyhemoglobin. Competitive effects of chloride ions and inositol hexakisphosphate.

We have extended our studies on the magnetic properties of carp carbonmonoxyhemoglobin and the dependence of these properties upon solution variables. Using an improved version of the superconducting magnetometer, we have found that the magnetic susceptibility of carp carbonomonxythemoglobin is sensitive to both inositol hexakisphosphate and chloride ion. The dependence upon chloride ion concentration is complex. At relatively low concentrations this anion reverses the effect of inositol hexakisphosphate, restoring paramagnetism. At higher chloride concentrations the protein is converted to a roughly diamagnetic state in the absence of inositol hexakisphosphate. Along with these suceptibility studies, we have examined the effects of these anions on other properties of carp carbonmonoxyhemoglobin. The positions of the Soret bands of human asd carp methemoglobin derivatives are correlated with spin state; changes in the magnetic suceptibility of carbobmonoxyhemoglobi are similarly associated with alterations in this spectral band. We have also examined the effects of these anions on the proton nuclear magnetic resonance specturm of carp carbonomonoxyhemoglobin. Both chloride and inositol hexakisphosphate alter the position of the position of the proton resonances in the ring-current-shifted region of the spectrum.