ドジョウの2成分系ヘモグロビンに関する研究-II : 酸素解離曲線について

概要

論文の詳細を見る
Oxygen equilibrium of loach hemolyzate and, components F and S which were separated from each other by starch block electrophoresis, was investigated by the spectrophotometric method2). Results were as follows: As shown in Figs. 1-3, the oxygen pressure of half saturation (P50) at physiological pH was below 2.0mm. Hg for the three samples. Thus, loach hemoglobin (Hb) may be emphasized to have the extraordinarily strong affinity to oxygen, which might enable this fish the peculiar intestinal respiration12). n Values in the HILLS equation of hemolyzate and component F were not so specific. On the other hand, component S showed the considerably low value of ca. 1.2 over all the pH range covered (pH 6.1-7.7). The BOHR effect was remarkably different between both components, F showing an apparent BOHR effect while S not at all. Considering also the fact that myoglobin was not found out in any tissue of this fish, this may suggest the possession of some myoglobin-like functions of component S in the blood (Figs. 1 and 2). In relation to the BOHR effect, the number of free sulfhydryl groups was determined of both components by the amperometric titration method4). Results showed that component F has ca. 8 free sulfhydryl groups per molecule but S has none, roughly corresponding with the RIGGS hypothesis5). Effect of temperature on the oxygen dissociation was found to be slighter for component S than for F (Figs. 5 and 6). The reaction heats in oxygenation of the hemolyzate and both components calculated from the VANT HOFFS equation were comparable to those of mammalian Hbs6) (Fig. 8). Effect of phosphate buffer concentration on oxygen dissociation was also slighter for component S (Figs. 9 and 10). The oxygen dissociation curves of hemolyzate largely differed from what was expected from the results of separated components (see Fig. 12). The magnitude of BOHR effect of the hemolyzate was unexpectedly large, just double that of component F, suggesting the occurrence of a strong interaction in the hemolyzate between both Hb components (Figs. 3 and 4). The temperature effect on the hemolyzate was more remarkable than on each separated component, while the effect of phosphate buffer concentration was less (Figs. 5-7 and 9-11). These facts also indicate the occurrence of the interaction mentioned above. If such an interaction actually exists in the blood of living loach, the physiological functions as supposed above for each component should be corrected. However, it is not yet clear whether it is true or not, because, firstly, Hb is much more concentrated in blood cells than in the hemolyzate solution used in this study and secondly, coexistence of both components in the same blood cells is not confirmed so far.

ドジョウの2成分系ヘモグロビンに関する研究-II : 酸素解離曲線について

スポンサーリンク

概要

著者

関連論文

スポンサーリンク