Magnetic and Spectral Properties of Carp Carbonmonoxyhemoglobin. Competitive Effects of Chloride Ions and Inositol Hexakisphosphate

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Abstract
Studies on the magnetic properties of HbCO2 and the dependence of these properties upon solution variables were extended. An improved version of the superconducting magnetometer showed that the magnetic susceptibility of carp carbonmonoxyhemoglobin is sensitive to both inositol hexakisphosphate and Cl. The dependence upon Cl ion concentration is complex. At relatively low concentrations, this anion reverses the effect of inositol hexakisphosphate, restoring paramagnetism. At higher Cl concentrations the protein is converted to a roughly diamagnetic state in the absence of inositol hexakisphosphate. Along with these susceptibility studies, the effects of these anions on other properties of carp HbCO2 were examined. The positions of the Soret bands of human and carp methemoglobin derivatives are correlated with spin state; changes in the magnetic susceptibility of HbCO2 are similarly associated with alterations in this spectral band. The effects of these anions on the proton NMR spectrum of carp HbCO2 were examined. Both Cl and inositol hexakisphosphate alter the position of the proton resonances in the ring-current-shifted region of the spectrum.