title: Pernin: a novel, self-aggregating haemolymph protein from the New Zealand green-lipped mussel, Perna canaliculus (Bivalvia: Mytilidae).
abstract: A protein, designated pernin, found in the New Zealand green-lipped mussel, comprises almost all of the protein in cell-free haemolymph. It occurs as large, aggregate structures of several hundred units resembling small virus-like particles. Pernin is a non-pigmented, glycosylated protein, composed of 497 amino acids, which has an estimated molecular mass of 60 kDa. It is exceptionally rich in histidine (13.7%) and aspartic acid (12.3%), amino acids both known to participate in the binding of divalent metal cations. In addition, pernin has serine protease inhibitor activity, likely due to a sequence of eight N-terminal amino acid residues, separated from the remainder of the protein via a histidine-aspartate spacer. The pernin monomer comprises three regions of obvious sequence duplication. These make up approximately 95% of the pernin molecule and have sequences clearly homologous to the active-site domain of Cu-Zn SODs (superoxide dismutases). Despite several of the metal ion co-ordinating histidine residues being retained, pernin contains no Cu or Zn. It is, however, associated with Fe with an apparent stoichiometry of 1 atom of Fe to 6 molecules of pernin. Since pernin has no demonstrable SOD activity, these SOD-derived sequences presumably have been modified for another function.
authors: The Horticulture and Food Research, Institute of New Zealand Ltd., Mt. Albert Research Centre, Private Bag, 92169, Auckland, New Zealand. pscotti@hortresearch.co.nz
authors: P D
authors: PD
authors: Scotti
authors: S C
authors: SC
authors: Dearing
authors: D R
authors: DR
authors: Greenwood
authors: R D
authors: RD
authors: Newcomb
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000925:Anticoagulants / Q000097:blood / Q000737:chemistry* / Q000302:isolation & purification; D001483:Base Sequence; D049872:Bivalvia / Q000737:chemistry*; D001798:Blood Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D002942:Circular Dichroism; D019281:Dimerization; D006023:Glycoproteins / Q000097:blood / Q000737:chemistry* / Q000302:isolation & purification; D006458:Hemolymph / Q000737:chemistry*; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D009520:New Zealand; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D015842:Serine Proteinase Inhibitors / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification; D013917:Thrombin / Q000037:antagonists & inhibitors
chemical_list: D000925:Anticoagulants; D001798:Blood Proteins; D006023:Glycoproteins; D015842:Serine Proteinase Inhibitors; C442279:pernin protein, Perna canaliculus; D007501:Iron; D013917:Thrombin