Journal of the Mass Spectrometry Society of Japan
Online ISSN : 1880-4225
Print ISSN : 1340-8097
ISSN-L : 1340-8097
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Volume 56, Issue 1
Displaying 1-5 of 5 articles from this issue
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REGULAR PAPERS
  • Comparative Characterization of Ribosomal Proteins of Lactic Acid Bacteria by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry
    Kanae TERAMOTO, Liwei SUN, Hiroaki SATO, Masaki TORIMURA, Hiroaki TAO, ...
    2008 Volume 56 Issue 1 Pages 1-11
    Published: February 01, 2008
    Released on J-STAGE: February 26, 2008
    DOIhttps://doi.org/10.5702/massspec.56.1
    JOURNAL FREE ACCESS
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    Ribosomal subunit proteins of eight genome-sequenced lactic acid bacteria (LAB) were characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to provide a guideline for selecting reliable biomarkers used for the rapid identification of LAB. Subunit proteins with molecular weight over ca. 20,000 were typically difficult to detect. This phenomenon appeared to be due to the mass discrimination effect in MALDI-MS. Conserved post-translational modifications excluding N-terminal methionine loss were investigated by comparing the mass differences from sequence masses calculated from the amino acid sequences of the proteins with the post-translational modifications. Various errors in the amino acid sequences of the subunit proteins registered in protein databases could be detected by comparing amino acid sequences, and corrected by inspecting gene sequences. By eliminating the subunit proteins with higher molecular weight and post-translational modifications as well as other difficult to detect subunit proteins, 27 subunit proteins were finally selected as the reliable biomarkers.
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  • Study on Type Analysis of Crude Oil and Petroleum Products by Gas Chromatography/Time-of-Flight Mass Spectrometry
    Masaaki UBUKATA, Akihiko KUSAI, Junichi OSUGA, Kazuo TANAKA, Takeo KAN ...
    2008 Volume 56 Issue 1 Pages 13-19
    Published: February 01, 2008
    Released on J-STAGE: February 26, 2008
    DOIhttps://doi.org/10.5702/massspec.56.13
    JOURNAL FREE ACCESS
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    Type analysis of crude oil and petroleum products has been studied using a gas chromatograph/time-of-flight mass spectrometer. The use of inert fused silica capillary tube inlet/field ionization (blank tube inlet/FI) is a suitable method for analyzing low boiling point components. Field ionization (FI) and field desorption (FD) methods are classified as soft ionization. Therefore, those ionization methods are used to analyze samples in which the molecular ion is hardly detected on electron ionization, as in the case of hydrocarbons. Type analysis using blank tube inlet/FI, capillary gas chromatography/FI (GC/FI), and FD mass spectra provides useful information, such as the average molecular weight. We examined the composition of crude oil and some petroleum products by type analysis using blank tube inlet/FI, capillary GC/FI, and FD. We carried out type analysis using six series of components. These were CnH2n+2, CnH2n, CnH2n-2, CnHn-4, CnHn-6, and CnHn-8. The averaged molecular weight by FD was much higher than that by blank tube inlet/FI, because it is difficult to measure low boiling point components by FD. In the blank tube inlet/FI method, all components were introduced and ionized. Therefore, this method is much more suitable than other methods for evaluating the composition of crude oil and petroleum products.
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COMMENTARY
Letter to the Editor
Letter from the Editor-in-Chief
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