title: Mass spectrometric characteristics and kinetics of iron release in visceral mass of Saccostrea cucullata.
abstract: Ferritins with electrophoretic homogeneity were prepared from the visceral mass of Saccostrea cucullata in batch. The native PAGE approach showed similar electrophoretic mobility among pig pancreatic ferritin, liver ferritin of Dasyatis akajei, and visceral mass ferritin of Saccostrea cucullata. SDS-PAGE indicated that the Saccostrea cucullata visceral ferritin (SCVF) consisted of a single subunit type and had a molecular weight (MW) of approximately 20 kDa, suggesting that the protein shell in SCVF was composed of a single subunit. In addition, peptide mass fingerprinting and transmission electron microscopy were used to identify SCVF further, and to observe its molecular structure. We found that the molecular structure in SCVF was similar to that of most mammalian ferritins, which are composed of a protein shell and an iron core. The results of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry under the assistance of an acidic matrix, sinapic acid, also showed that SCVF was composed of a single subunit type and its subunit MW was calculated to be 19871.042 Da in the absence of heme. Kinetics analysis revealed that the complete process of iron release fitted the law of a first-order reaction, which is similar to that of most ferritins in mammals. Similar to bacterial ferritin, studies indicated that the shell consisted of a single subunit type and showed similar kinetics of iron release, suggesting that this subunit plays two important roles in iron release and storage, and that it shows different stability and intensity of interaction in carrying out its physiological functions in SCVF.
authors.affiliation: State Key Laboratory of Stress Cell Biology (Xiamen University), School of Life Sciences, Xiamen University, Xiamen, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhu
authors.forename: Cai-Huan
authors.initials: CH
authors.lastname: Ke
authors.forename: He-Qing
authors.initials: HQ
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018940:Elasmobranchii; D004591:Electrophoresis, Polyacrylamide Gel; D005293:Ferritins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010125:Ostreidae / Q000737:chemistry*; D010179:Pancreas / Q000737:chemistry / Q000378:metabolism; D010449:Peptide Mapping; D021122:Protein Subunits; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013552:Swine
chemical_list: D021122:Protein Subunits; D005293:Ferritins; D007501:Iron