The giant extracellular hemoglobin of Lumbricus terrestris was investigated in the oxygenated, deoxygenated and reoxygenated state using small angle X-ray scattering. Scattering experiments of the oxygenated state of the protein yielded a radius of gyration of 10.71 +/- 0.02 nm, a maximum diameter of 29.37 +/- 0.21 nm and a volume of 6200 +/- 200 nm3. The values for the deoxygenated state of the hemoglobin are smaller than the values for the oxygenated state, but the differences hardly exceed the limits of error.
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