title: Complete amino acid sequence of dioxygen-binding functional unit of the Rapana thomasiana hemocyanin.
abstract: The complete amino acid sequence of the Rapana thomasiana hemocyanin N-terminal functional unit Rta was determined by direct sequencing and matrix-assisted laser desorption ionization mass spectrometry of the protein and peptides obtained by cleavage with EndoLysC proteinase, TPCK-trypsin and cyanogen bromide. The single polypeptide chain consists of 407 residues. This is the first report on the primary structure of a dioxygen-binding unit from a marine gastropod hemocyanin and of an N-terminal domain from a molluscan dioxygen carrier. Comparison with the sequences of other molluscan hemocyanin functional units shows an average identity of 48 +/- 5 %. Inspection of the Rta sequence revealed residues 27 and 250 as carbohydrate attachment sites. Conclusions about the molecular evolution of the molluscan hemocyanin dioxygen-binding functional units are made.
authors.affiliation: Abteilung für Physikalische Biochemie, Physiologisch-chemisches Institut der Universität Tübingen, Hoppe-Seyler-Str. 4, Tübingen, D-72076, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Stoeva
authors.forename: K
authors.initials: K
authors.lastname: Idakieva
authors.forename: N
authors.initials: N
authors.lastname: Genov
authors.forename: W
authors.initials: W
authors.lastname: Voelter
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D006433:Hemocyanins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism*; D017421:Sequence Analysis; D012908:Snails
chemical_list: D006433:Hemocyanins; D010100:Oxygen