Composition, Structure and Function from Endopeptidease of Aplysia Egg Analyzed with Matrix Assisted Laser Desorption Ionization-Time of Flight-Mass Spectrometry

Determination of Perfluorooctane Sulfonates (PFOS) in Four Chemical Materials by HPLC/MS/MS

A rapid method based on high performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS) with accelerated solvent extraction (ASE) or solid phase extraction (SPE) was developed for quantitative determination of perfluorooctane sulfonate (PFOS) in the coatings of nonstick pot, food packaging materials, waterborne coatings containing fluoride and fire-fighting foams. The linear calibration curve was obtained in the range of 0.002 - 0.1 μg/mL with a linear correlation coefficient (R2) of 0.998 or 0.999. The recovery for PFOS was in the range of 93.4 - 103% with relative standard deviation of 0.48 - 3.59%. The detection limit for PFOS was 0.4 μg/m2 with a signal-to-noise ratio of 10 for the coatings of nonstick pot and the food packaging materials, and 0.0002% for waterborne coatings containing fluoride and fire-fighting foams, both of which meet the restriction requirement for PFOS content in these chemical materials and consumer products in the EU directives.

Mass spectrometric characteristics and kinetics of iron release in visceral mass of Saccostrea cucullata

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.

A metabonomic characterization of CCl4-induced acute liver failure using partial least square regression based on the GC/MS metabolic profiles of plasma in mice

This work characterized the metabolism disorders of acute liver failure (ALF) induced by carbon tetrachloride (CCl(4)) in a mouse model with different dosage of intoxication (100, 500 and 1000 mg/kg). Metabolic profiles of mice plasma were detected by gas chromatography/mass spectrometry (GC/MS) after chemical derivatization. Here an effective information-extracting approach was implemented on the basis of partial least square regression analysis (PLS-RA). PLS modeling was achieved with two kinds of Y-vectors for the acquired metabonomics data and eight metabolites with different changing behaviors were selected. ALF of mice induced by CCl(4) was characterized by the elevation of glutamate, citrate, serine and threonine, as well as the decrease of alpha-glycerophosphate, docosahexaenoic acid, palmitic acid and oleic acid in plasma. The difference in the concentrations of serine, threonine, palmitic acid and oleic acid remained insignificant between the control and 100mg/kg groups, while significant distinction appeared when comparing the control and two higher dosed groups. The underlying regulation of CCl(4)-perturbed metabolic pathways was discussed according to the selected metabolites. The present study demonstrated a great potential of PLS-RA in exploiting a comprehensive metabolic effects of CCl(4) intoxication and its efficient capability to reveal the hepatotoxic mechanism of ALF induced by reactive oxygen species (ROS).