Immunochemical and physicochemical properties of haptoglobin, abtihemoglobin antibody, and their complexes with hemoglobin

The immunochemical properties of haptoglobin which binds specifically with hemoglobin were compared with those of antihemoglobin A₁ antibody. Hemoglobin-haptoglobin shows neither precipitation reaction nor complement fixation reaction under conditions in which hemoglobin-antihemoglobin antibody shows these immunological reactions. From these observations, the absence of lattive formation between hemoglobin and haptoglobin was suggested. Antihuman hemoglobin antibody binds deoxygenated human hemoglobin and hemoglobin-haptoglobin complex, both of which human haptoglobin does not. On the other hand, although human haptoglobin binds hemoglobins of horse, rabbit, and frog, antihuman hemoglobin antibody does not. And from the data on circular dichroism spectra of hemoglobin-haptoglobin complex and hemoglobin-antihemoglobin antibody complex, the differences in environmental structure around the heme between hemoglobin-haptoglobin complex and hemoglobin-antihemoglobin antibody complex are clarified which may have some connection with the differences in immunochemical reactions between these two complexes.