Striped mullet (Mugil cephal) hemoglobin system: multiplicity and functional properties

The most frequent (90%) phenotype of the hemoglobin system of M. cephalus presented two major hemoglobins, the more anodal HbI accounting for approximately 70% of the total. The two hemoglobin components separated by ion-exchange chromatography were analyzed by reverse-phase HPLC and electrospray ionization-mass spectrometry which revealed a more complex pattern: HbI consists in four different globins, two b(namedb1andb3) and two co-eluting achains(a1 and a2); HbII consists in three globins, one bchain(namedb2) and the same a1 and a2 present in HbI. Theoxygen-binding properties of both hemoglobin components purified by DEAE cellulose were almost identical to those of the hemolysate: stripped hemoglobins howed a large Bohr effect which was enhanced by chloride ions and, a ta larger extent, by organic phosphates which, at acidic pH values gave rise to the Root effect. A series of oxygen-binding experiments at increasing GTP concentrations was carried out in order to compare GTP-binding activities in the absence and presence of physiological amount sofchloride