In this study, we explored a new approach for generating ions of organics and biomolecules using contactless atmosphericpressure ionization (C-API). That is, a tapered capillary (~20 cm) was connected to a syringe, which was coupled to asyringe pump for providing a given flow rate to introduce sample solution to the proximity of a mass spectrometer. The gasphase ions derived from analytes were readily formed in the capillary outlet, which was very close to the mass spectrometer(~1 mm). No external electric connection was applied on the capillary emitter. This setup is very simple, but it can function as anion source. This approach can be readily used for the analysis of small molecules such as amino acids and large molecules suchas peptides and proteins. The limit of the detection of this approach was estimated to be ~10 pM when using bradykinin as thesample. Thus, we believe that this approach should be very useful for being used as an alternative ion source because of its lowcost, high sensitivity, simplicity, and ease of operation.
Cellular processes such as proliferation, differentiation, and adaptation to environmental changes are regulated byprotein phosphorylation. In order to enhance the understanding of molecular dynamics for biological process in detail, it is necessaryto develop sensitive and comprehensive analytical methods for the determination of protein phosphorylation. Neural stemcells hold great promise for neural repair following an injury or disease. In this study, we made differentiated oligodendrocytesfrom human neural stem cells using over-expression of olig2 gene. We confirmed using quantitative phosphoproteome analysisapproach that combines stable isotope labeling by amino acids in cell culture (SILAC) and TiO2 micro-column for phosphopeptideenrichment with MS2 and MS3 mass spectrometry. We detected 275 phosphopeptides which were modulated at least 2-foldbetween human neural stem cells and oligodendrocytes. Among them, 23 phosphoproteins were up-regulated in oligodendrocytesand 79 phosphoproteins were up-regulated in F3 cells.
The ultraviolet (UV) degradation products of photochromic naphthoxazine and naphthopyran derivatives in acetonitrilewere separated and identified using liquid chromatography-mass spectrometry (LC-MS). Photodegradation resulted in oxidationof products.
Mollugin isolated from Rubia cordifolia is known to have anti-inflammatory, anti-cancer, and anti-viral activities. Inthe present study, a cocktail probe assay and LC-MS/MS were used to investigate the modulating effect of mollugin on cytochromeP450 (CYP) enzymes in male ICR mice. After mollugin was orally administrated to mice at the 20, 40, or 80 mg/kg for3 days, the activities of CYP in hepatic S-9 fractions were investigated. Unlike the selective inhibitory effect of mollugin onCYP1A2-catalyzed phenacetin O-deethylation in vitro, mollugin only significantly inhibited the activity of CYP2E1-catalyzedchlorzoxazone 6-hydroxylase in vivo. The activities of other CYPs were only slightly altered by mollugin. The results of thisstudy suggest that mollugin might cause herb-drug interactions via the selective inhibition of CYP2E1 in vivo.
An experimental study on the nascent product of the OH heterogeneous reaction with NaCl was performed under dryand wet conditions using a bead-filled flow tube system coupled to a high-pressure chemical ionization mass spectrometer. Theozone concentration in the flow tube for the atomic hydrogen removal was varied in order to control the conversion reaction ofmolecular chlorine into HCl for the identification of the nascent product. The mass spectrometric observation was that the O3introduction reduced the concentration HCl, while it increased the concentration of Cl2 and ClO. Based on the experimentalresults, we suggest that the nascent product of the titled reaction is gaseous Cl2, which is followed by fast conversion into HCl inpresence of H. No significant difference in the concentration profile between under dry and wet (RH = 2%) conditions wasobserved.