Igarashi Y, Kimura K, Kajita A
Biochem Int. 1985 Apr;10(4):611-8.
The effect of calcium and magnesium ions on the oxygen equilibrium of Eisenia hemoglobin was investigated by using an automatic oxygenation apparatus. On addition of calcium chloride (20 mM, pH 7.5), oxygen affinity and cooperativity (nmax) of the hemoglobin increased markedly (p 50:3.82 mmHg, nmax :9.76). The effect of magnesium on the oxygen equilibrium was weaker than that of calcium. The top asymptotes of the oxygen equilibrium curve shifted to the left by adding cations whereas the bottom asymptotes remained almost unchanged. The free energy of heme-heme interaction (delta GR,T) also increased remarkably. These results imply the binding of calcium to Eisenia hemoglobin in the oxygenated form and its physiological role in modulating the oxygen affinity and cooperativity.
利用自动充氧装置研究了钙和镁离子对赤子爱胜蚓血红蛋白氧平衡的影响。添加氯化钙（20 mM，pH 7.5）后，血红蛋白的氧亲和力和协同性（nmax）显著增加（p50：3.82 mmHg，nmax：9.76）。镁对氧平衡的影响比钙弱。添加阳离子后，氧平衡曲线的上渐近线向左移动，而下渐近线几乎保持不变。血红素-血红素相互作用的自由能（δGR,T）也显著增加。这些结果表明钙以氧合形式与赤子爱胜蚓血红蛋白结合及其在调节氧亲和力和协同性方面的生理作用。
