S. Demuynck et N. Dhainautcourtois, IDENTIFICATION OF EXTRACELLULAR HEMOGLOBIN AS THE MAJOR HIGH-MOLECULAR-WEIGHT CADMIUM-BINDING PROTEIN OF THE POLYCHAETE ANNELID NEREIS-DIVERSICOLOR, Comparative biochemistry and physiology. C. Comparative pharmacologyand toxicology, 106(2), 1993, pp. 467-472
1. A high molecular weight cadmium-binding protein called MP I was iso
lated from Nereis diversicolor exposed to 20 ppm of cadmium (CdCl2) fo
r 4 days via sea water. 2. The protein had a molecular weight comprisi
ng between 20 x 10(6) and 1.5 x 10(6) Da. It shows high absorptions at
280 and 415 nm and contained iron in addition to cadmium. 3. Two dime
nsional SDS-PAGE of unreduced and reduced MP I revealed a dissociation
pattern similar to that of extracellular haemoglobins of polychaetes
and oligochaetes. 4. Furthermore, negatively stained MP I molecules ex
amined by conventional transmission electron microscopy showed the com
mon appearance of extracellular haemoglobins of annelids, 5. Evidence
of the extracellular haemoglobin nature for the MP I was found by the
identical chromatographic behaviour of MP I with the main Nereis blood
component and, by the labelling of blood vessel content with Cd-109 v
isualized by autoradiography on paraffin-embedded sections of exposed
Nereis.