title: Physical studies of the hemocyanin of the marine gastropod, Kelletia kelleti (Forbes).
abstract: 1. The hemocyanin of the Californian whelk, Kelletia kelleti, investigated at pH and ionic conditions close to physiological, has a molecular weight close to 9.0 x 10(6) and a sedimentation constant of 114S, characteristic of the di-decameric structure of molluscan hemocyanins. Light-scattering measurements at pH 8.0, 0.05 M Mg2+, 0.01 M Ca2+ gave a molecular weight of 9.0 +/- 0.6 x 10(6), and scanning transmission electron microscopy produced nearly the same particle mass of 9.22 +/- 0.50 x 10(6) daltons (Da). 2. Light-scattering measurements on the fully dissociated monomers in the presence of 8.0 M urea and at pHs 10.6 and 11.0 gave molecular weights of 4.50 x 10(5)-4.91 x 10(5), that are close to one-twentieth of the mass of the parent di-decameric hemocyanin assembly. 3. Changes in pH produced a bell-shaped molecular weight profile, with molecular weights close to 9.0 x 10(6) in the pH region of about 5.5-8.0, and progressive dissociation to 4.5 x 10(5) Da monomers in the region below pH 4.0 and above pH 9.0 or 10, depending on the absence or presence of stabilizing Mg2+ ions (0.01 M). 4. In the absence of divalent ions some aggregation of hemocyanin was found at pHs close to 5.0, with observed molecular weights above 10 x 10(6) (investigated at a hemocyanin concentration of 0.10 g/l). The early studies of Condie and Langer (Science 144, 1138-1140, 1964) had shown that Kelletia kelleti hemocynanin aggregates at acidic pHs close to the isoelectric point, forming linear polymers of the hemocyanin di-decamers.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Chemistry, Fordham University, Bronx, NY 10458.
authors.forename: T T
authors.initials: TT
authors.lastname: Herskovits
authors.forename: J
authors.initials: J
authors.lastname: Zou
authors.forename: M G
authors.initials: MG
authors.lastname: Hamilton
mesh_terms: D000818:Animals; D006433:Hemocyanins / Q000737:chemistry* / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D008027:Light; D017348:Microscopy, Electron, Scanning Transmission; D008970:Molecular Weight; D011487:Protein Conformation; D011489:Protein Denaturation; D012542:Scattering, Radiation; D012908:Snails / Q000737:chemistry*
chemical_list: D006433:Hemocyanins