Properties of hemocyanins isolated from Amazon river arthropods and molluscs

Abstract 1. Hemocyanins from four organisms inhabiting the Amazon River were isolated and partially characterized. 2. Three arthropodan species ( Dilocarcinus pagei cristatus, Silviocarcinus pardalinus and Macrobrachium amazonicum ) possess hemocyanins whose subunit structure is remarkably simple. Regular and SDS polyacrylamide disc electrophoresis revealed predominantly single bands and no polymorphisms. 3. Oxygen-binding experiments showed that the three arthropodan hemocyanins possess large positive Bohr effects and pH dependence in the degree of subunit interaction. 4. The hemocyanin of one mollusc, Pila sp., was studied and its subunit size appears to be similar to that of other molluscan hemocyanins, i.e. a polypeptide of mol. wt 400,000. In the hemolymph, Pila hemocyanin probably exists as a mixture of 100 and 124 S aggregates. 5. The oxygen binding properties of the large molecules of Pila hemocyanin are notable because of their low cooperativity and lack of a strong pH-dependence.