title: Haemoglobin from the tadpole shrimp, Lepidurus apus lubbocki Characterization of the molecule and determination of the number of polypeptide chains.
abstract: Haemoglobin from the tadpole shrimp, Lepidurus apus lubbocki, was found to have a sedimentation coefficient (s020,w) of 19.3 +/- 0.2 S and a molecular weight, as determined by sedimentation equilibrium, of 798000 +/- 20000. The amino acid composition showed the lack of cysteine and cystine residues. A haem content of 3.55 +/- 0.03% was determined, corresponding to a minimal mol.wt. of 17400 +/- 200. The pH-independence in the range pH 5-11 of the sedimentation coefficient indicates a relatively high stability of the native molecule. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis gave one band with mobility corresponding to a mol.wt. of 34000 +/- 1500. The molecular weight of the polypeptide chain was determined to be 32800 +/- 800 by sedimentation equilibrium in 6 M-guanidinium chloride and 0.1 M-2-mercaptoethanol. The findings indicate that Lepidurus haemoglobin is composed of 24 identical polypeptide chains, carrying two haem groups each.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002499:Centrifugation, Density Gradient; D055598:Chemical Phenomena; D002621:Chemistry; D033364:Decapoda / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D006454:Hemoglobins; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis*
chemical_list: D000596:Amino Acids; D006454:Hemoglobins; D010455:Peptides