title: The hemocyanin of the Californian black sea hare, Aplysia vaccaria Winkler.
abstract: The hemocyanin of the Californian black sea hare. Aplysia vaccaria exists in solution largely as a di-decameric protein with a molecular weight of close to 8.0 x 10(6) and a sedimentation coefficient of about 92 S. Light-scattering measurements at pH 8.0, 0.1 M Tris, 0.05 M Mg2+, 0.01 M Ca2+ gave a molecular weight of 8.0 +/- 0.6 x 10(6), and scanning transmission electron microscopic determinations (STEM) gave a slightly higher particle mass of 8.49 +/- 0.41 x 10(6) daltons. Measurements using the STEM method gave a particle mass of 4.27 +/- 0.26 x 10(6) daltons for the dissociated half-molecules or decamers. Light-scattering measurements on the dissociated monomers at pH 11.1 and in 8.0 M urea gave molecular weights of 4.74 x 10(5). Sedimentation measurements in the presence of 0.01 M Mg2+ indicate that the hemocyanin of A. vaccaria is largely in the di-decameric form in the pH region from about 5.0 to 8.0. Above pH 8.0 the hemocyanin di-decamers are found to dissociate to half-molecules or decamers, followed by dissociation to dimers and monomers as the pH is increased above pH 9.0.
authors.affiliation: Department of Chemistry, Fordham University, Bronx, New York 10458, USA.
authors.forename: T T
authors.initials: TT
authors.lastname: Herskovits
authors.forename: M D
authors.initials: MD
authors.lastname: Edwards
authors.forename: M G
authors.initials: MG
authors.lastname: Hamilton
mesh_terms: D000818:Animals; D001048:Aplysia / Q000737:chemistry*; D019791:Guanidine; D006146:Guanidines; D006433:Hemocyanins / Q000737:chemistry* / Q000648:ultrastructure; D006458:Hemolymph / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008027:Light; D017348:Microscopy, Electron, Scanning Transmission; D008970:Molecular Weight; D011487:Protein Conformation; D012542:Scattering, Radiation; D014508:Urea
chemical_list: D006146:Guanidines; D014508:Urea; D006433:Hemocyanins; D019791:Guanidine