The hemoglobins of a fresh-water teleost, Cichlasoma cyanoguttatum (Baird and Girard). II. Subunit structure and oxygen equilibria of the isolated components

Abstract

Three major components constitute at least 80% of the total hemoglobin in hemolysates of the Rio Grande cichlid, Cichlasoma cyanoguttatum. All three of these appear to share a common β chain. Two components have unique α chains, and the other component has both of these unique α chains. Two of the major components have identical oxygen equilibria. The effects of pH (Bohr effect) and of adenosine triphosphate are the same for each of the three components. Although one of the components has a slightly higher oxygen affinity than the other two the effects of pH and of adenosine triphosphate appear to be indistinguishable in the different components. The Hill coefficient, n, is pH-dependent for all components. The data indicate that the ion exchange chromatography was without effect on the oxygen-binding properties. The oxygen equilibria of the components cannot be interpreted in terms of dimers and appear to require a tetrameric structure of the hemoglobin in the concentration range studied.