Effects of magnesium and calcium on the oxygenation reaction of erythrocruorin from the marine polychaete Arenicola marina and the terrestrial oligochaete Lumbricus terrestris.

Oxygenation function of annelid erythrocruorin (Er) is affected by Mg and Ca concentration in the blood. Four classes of responses may be encountered in different species: 1) Mg=Ca (equal effects), 2) Mg>Ca, 3) Mg