Oxido-reductive reactions of sulfhemoglobin with various reagents associated with changes in conformation of the...

The optical peaks at Soret region and near at 620 nm of sulfhemoglobin (sulfHb) shifted from 419.5 nm to 423 nm and from 623 nm to 619 nm, respectively, according to the decrease in oxygen concentrations of the sulfHb solution (1 atm to zero atm). This shift of optical peaks was strengthened by the addition of inositol hexaphosphate (P6-inositol), a strong allosteric effector of Hb. Thus the shift of the optical peaks seems to reflects the changes in conformation of sulfHb. In order to clarify the relationship between the conformation of sulfHb and the reactivity of the protein with various reagents, we studied the oxidation and reduction reaction of the protein with ascorbic acid, ferricyanide and nitrite under aerobic and anaerobic conditions. The results suggested that the rate of oxido-reductive reactions of ferrous and ferric sulf Hbs with these compounds are associated with the conformation of the protein.