STUDIES ON MULTIPLE HEMOGLOBINS OF EEL-II

Abstract

Oxygen equilibrium of components F and S, which were separated from each other by starch block electrophoresis, was studied by the spectrophotometric method2). The BOHR effect on the oxygen dissociation curve was clearly different between components F and S (Figs. 3 and 4), the oxygen pressure at half saturation (p50) of the former increasing considerably with decreasing pH, while that of the latter was little affected (Fig. 5). The close relation between the magnitude of the BOHR effect and the number of free sulfhydryl groups of Hb4), was ascertained also with these components (Fig. 6). In the case of component F, the sigmoidal character (n value in the HILL's equation > 1) of the dissociation curve at higher pH's changed into the hyperbolic one (n ?? 1) at lower pH's, whereas n for S remained at a constant value of about 2.3 (Figs. 7 and 8). These differences in the mode of the BOHR effect may be responsible for the discontinuity of dissociation curve observed in the case of hemolyzate with pH values below 7 (Fig. 2). The oxygen affinity in the physiological pH region differed between both components, p50 of component F being larger than component S. Effect of temperature on the dissociation curve was remarkable for both components, p50 of which increased with increasing temperature (Figs. 10 and 11). Heat of oxygenation per mole oxygen for both components was comparable to that of mammalian Hb8) (refer to Fig. 12). Effect of phosphate buffer concentration was more remarkable on component F than on S, in the same way as the BOHR effect (Figs. 13 and 14). The n value of each component decreased noticeably with increasing concentration of the buffer, to which may be partly due the crossing of two dissociation curves at concentrations of 0.5 and 1.0M. These facts were strongly reminiscent of the corresponding components of chum salmon2) Components F and S of the two kinds of fishes may be compared to the Hb of marine fish (lower oxygen affinity and stronger BOHR effect) and that of fresh-water fish (higher oxygen affinity and poorer BOHR effect), respectively. Blood specimens from some individuals were spectrophotometrically determined of relative amounts of both pigments (Fig. 1). There was a close relation between the proportion and body length, the proportion of component S decreasing with increasing body length, which is in a striking contrast to the case of chum salmon (Table 1). It may be guessed that such a difference stems from the ecological difference between both fishes, i. e., that eel is a catadromous fish, while chum an anadromous one.