Functional Properties of Native and Reconstituted Hemoglobins from Chironomus thummi thummi

A procedure for preparation of native globin from Chironomus hemoglobin has been developed and functional properties of native and reconstituted (proto‐, meso‐ and deutero‐) hemoglobins have been studied. Globin differs from the corresponding hemoglobin in a number of properties, but the differences are reversible and vanish on addition of protoheme. The oxygen affinity of protohemoglobin (p1/2 = 0.7 mm Hg at 20°C) is lower than that of meso‐ and deutero‐hemoglobins, respectively, the shape of oxygenation curve of all three hemoproteins being consistent with a simple mass‐law formulation. While protohemoglobin shows a small but definite Bohr effect, the oxygen affinity of the deuteroderivative is pH independent. Kinetic results show that binding of oxygen, carbon monoxide and ethylisocyanide to native and reconstituted Chironomus hemoglobins is a simple process, since the association process follows bimolecular behaviour and the dissociation reaction conforms to first‐order kinetics.