著者

Tokuma Fukuoka Sayaka Nakamura Tomotake Morita Takayuki Ohmura Masahiro Kotani Yasuhide Naito Hiroaki Sato

出版者

Japan Oil Chemists' Society

雑誌

Journal of Oleo Science (ISSN:13458957)

巻号頁・発行日

pp.ess21084, (Released:2021-07-09)

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Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a promising tool for the screening of glycolipid-type biosurfactants (BSs) from a crude extract of microbial products. However, it is unsuitable for the detection of lower molecular weight products because the observed ions are overlapped with matrix-derived ions at lower mass range. In this study, we applied a “matrix-free” surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) analysis using a through-hole alumina membrane as an ionization-assisting substrate. Using this method, we could detect a variety of lower molecular weight products in an extract of a glycolipid BS producer with good sensitivity. In addition, the culture solution could be analyzed directly by this method.

著者

Sayaka Nakamura Hiroaki Sato Thierry N. J. Fouquet

出版者

The Mass Spectrometry Society of Japan

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.9, no.1, pp.A0079, 2020-02-06 (Released:2020-02-06)

参考文献数

18

被引用文献数

2

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The Kendrick analysis is used for the processing and visualization of mass spectra obtained from polymers containing C, H, O and/or Si with simple isotopic patterns (monoisotope=lightest isotope=most intense isotope for short chains). In the case of heteroatoms with complex isotopic patterns, the impact of the chosen isotope on point alignments in Kendrick plots has not been examined extensively. Rich isotopic patterns also make the evaluation of the mass and nature of the repeating unit and end-groups more difficult from the mass spectrum in the case of unknown samples due to the number of peaks and the absence of a monoisotopic peak. Using a polybrominated polycarbonate as running example, we report that horizontal point alignments can be obtained in a Kendrick plot using the mass of the most abundant isotope instead of the monoisotopic mass as is usually done. Rotating the plot (“reverse Kendrick analysis”) helps to accurately evaluate the mass of the most abundant isotope of the repeating unit, as well as the nature of the brominated neutral expelled upon gentle heating (debromination or dehydrobromination). The whole procedure is then applied to the characterization of an unknown polybrominated flame retardant in an industrial formulation before and after heating.

著者

Sayaka Nakamura Hiroaki Sato Reiko Tanaka Takashi Yaguchi

出版者

日本質量分析学会

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.5, no.1, pp.A0049-A0049, 2016-11-10 (Released:2016-11-08)

参考文献数

28

被引用文献数

11

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We have previously proposed a rapid identification method for bacterial strains based on the profiles of their ribosomal subunit proteins (RSPs), observed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). This method can perform phylogenetic characterization based on the mass of housekeeping RSP biomarkers, ideally calculated from amino acid sequence information registered in public protein databases. With the aim of extending its field of application to medical mycology, this study investigates the actual state of information of RSPs of eukaryotic fungi registered in public protein databases through the characterization of ribosomal protein fractions extracted from genome-sequenced Aspergillus fumigatus strains Af293 and A1163 as a model. In this process, we have found that the public protein databases harbor problems. The RSP names are in confusion, so we have provisionally unified them using the yeast naming system. The most serious problem is that many incorrect sequences are registered in the public protein databases. Surprisingly, more than half of the sequences are incorrect, due chiefly to mis-annotation of exon/intron structures. These errors could be corrected by a combination of in silico inspection by sequence homology analysis and MALDI-TOF MS measurements. We were also able to confirm conserved post-translational modifications in eleven RSPs. After these verifications, the masses of 31 expressed RSPs under 20,000 Da could be accurately confirmed. These RSPs have a potential to be useful biomarkers for identifying clinical isolates of A. fumigatus.