Functional and structural properties of the hemoglobin components from Italian sturgeon (Acipenser Naccarii).

The structural and oxygen binding properties of Acipenser naccarii blood have been investigated. The electrophoretic analysis of the hemolysate of this sturgeon showed the presence of two hemoglobin components, each with a considerable globin multiplicity. Constituent globin chains were analyzed by urea-Triton acid polyacrylamide gel electrophoresis and isolated by high performance liquid chromatography. N-terminal amino acid sequence analysis revealed the presence of a N-terminal proline in two of the three alpha-chains present in the globin pattern, and the presence of a histidine residue in 2betaposition. Oxygen equilibria reveal a very low sensitivity of the individual hemoglobins to chloride ions and temperature; however, in the presence of organic phosphates the oxygen affinity of the hemoglobin components decreases strongly. In particular, when Guanosine-5-triphosphate (GTP) is added, the reduction of the oxygen affinity, at pH 7.4 and 20 oC, is 60% and 50%, respectively, for HbI (anodic component) and HbII (cathodic component). As the effect of protons is concerned, the small Root effect shown by total hemolysate at physiological conditions, seems to be due mainly to the cathodic component. On the whole, the functional properties shown by sturgeon hemoglobin components seem to be related to the particular physiological needs dictated by the environmental characteristics.