Structural characterization and oxygen binding properties of extracellular hemoglobin from the marine polychaete Eurythoe complanata

1. 1. Extracellular hemoglobin from the polychaete Eurythoe complanata has a sedimentation coefficient of 54 S. In the electron microscope, the molecule exhibits a two-layered hexagonal appearance characteristic of annelid extracellular hemoglobins. 2. 2. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis in the presence of 2-mercaptoethanol gave two main bands corresponding to mol. wts 21,000 and 34,000 and a faint band corresponding to mol. wt 25,000. 3. 3. In the pH range 4.6-10.5, oxygen binding showed little co-operativity (Hill coefficient ≤1.7). Small alkaline (φ = -0.09) and reverse acid (φ = 0.04) Bohr effects were observed. 4. 4. The oxygen equilibrium properties of Eurythoe hemoglobin were compared with those of other polychaete hemoglobins.