Gastropod haemocyanins: Dissociation of haemocyanins from Buccinum undatum, neptunea antiqua and Colus gracilis in the region pH 7.5–9.2

Abstract

1. 1. The pH-induced dissociation of the haemocyanins from the whelks, Buccinum undatum, Neptunea antiqua, and Colus gracilis was studied over the range pH 7.5–9.2. The native (100 S) molecule dissociated into half (60 S) and tenth (approx. 16 S) molecules, though this process was not complete for several hours. 2. 2. In some instances wholes, halves, and tenths co-existed at a certain pH value, and did not appear to be in rapid equilibrium with one another. Upon lowering the pH the dissociation was partly or wholly reversible depending on the species and the Mg 2+ or Ca 2+ concentration. 3. 3. Between pH 7.8 and 7.9 C. gracilis haemocyanin, unlike the other haemocyanins, existed entirely as half molecules. 4. 4. The so-called “tenth” molecules were not homogeneous. It is possible that they were in equilibrium with a smaller molecular species or that some slow irreversible modification of conformation was taking place.