title: Characterization of the extracellular haemoglobin of Haemopsis sanguisuga (L.).
abstract: The haemoglobin from the blood of the horseleech, Haemopsis sanguisuga (L.), had a sedimentation coefficient, SO20, w, of 59.11 +/- 0.55 S, and a molecular weight as determined by sedimentation equilibrium of 3.71 X 10(6)+/-9904 X 10(6). In the electron microscope the molecule appeared to be made up of two hexagonal plates, as is found with other worm haemoglobins, with dimensions 24.4+/-2.0 nm (across the hexagon) and 15.2+/-1.4 nm (height). The amino acid composition and spectrum were closely similar to those of the haemoglobins of other annelids (e.g. Lumbricus). The alpha-helical content, calculated from circular-dichroism measurements in the far-u.v. region, was 56-63%. The haem content was 2.49%, corresponding to a minimum molecular weight per haem group of 24 800, but detergent-gel electrophoresis indicated the presence of polypeptide chains of mol.wts. 12 600, 14 800, 15 500 and 25 100. The pH-induced dissociation of the native molecule yielded compotosol of Soya-bean root nodules.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D002942:Circular Dichroism; D006418:Heme / Q000032:analysis; D006454:Hemoglobins / Q000032:analysis*; D007865:Leeches / Q000032:analysis*; D008970:Molecular Weight; D010100:Oxygen; D010455:Peptides / Q000032:analysis
chemical_list: D000596:Amino Acids; D006454:Hemoglobins; D010455:Peptides; D006418:Heme; D010100:Oxygen