Characterization and improved separation of soybean leghemoglobins

An improved separation procedure is described for isolating five leghemoglobin components from the nodules of soybean plants. After a preliminary oxidation with ferricyanide, and separation from endogenous nicotinate at pH 9.2, the ferrileghemoglobins are separated by DEAE-cellulose chromatography using gradient elution with acetate buffer (pH 5.2). The components have been characterized by their acetate and nicotinate binding affinities, gel electrophoretic, visible, and circular dichroic spectra in the ultraviolet, Soret and visible regions. Two formerly unresolved components of leghemoglobin c have indistinguishable circular dichroic, electrophoretic, and ligand binding properties, but differ in their spin states as judged by their visible spectra, their amino acid analyses, and their tryptic maps.