SE130:/DS1

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Sample Set Information

ID TSE14
Title Chemical Assignment of Structural Isomers of Sulfur-Containing Metabolites in Garlic by Liquid Chromatography−Fourier Transform Ion Cyclotron Resonance−Mass Spectrometry
Description BACKGROUND:

The chemical assignment of metabolites is crucial to understanding the relation between food composition and biological activity.

OBJECTIVE:
This study was designed to detect and chemically assign sulfur-containing metabolites by using LC-Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS) in Allium plants.

METHODS:
Ultrahigh resolution (>250,000 full width at half-maximum) and mass accuracy (<1 mDa) by FTICR-MS allowed us to distinguish ions containing sulfur isotopes ((32)S and (34)S).

RESULTS:
Putative 69 S-containing monoisotopic ions (S-ions) were extracted from the metabolome data of onion (Allium cepa), green onion (Allium fistulosum), and garlic (Allium sativum) on the basis of theoretical mass differences between (32)S-ions and their (34)S-substituted counterparts and on the natural abundance of (34)S. Eight S-ions were chemically assigned by using the reference data according to the guidelines of the Metabolomics Standards Initiative. Three ions detected in garlic were assigned as derived from the isomers γ-glutamyl-S-1-propenylcysteine and γ-glutamyl-S-2-propenylcysteine and as S-2-propenylmercaptoglutathione on the basis of differences in key product ions identified in reference tandem MS spectra.

CONCLUSION:
The ability to discriminate between such geometric isomers will be extremely useful for the chemical assignment of unknown metabolites in MS-based metabolomics.

Authors Ryo Nakabayashi, Yuji Sawada, Morihiro Aoyagi, Yutaka Yamada, Masami Yokota Hirai, Tetsuya Sakurai, Takahiro Kamoi, Daryl D Rowan, Kazuki Saito
Reference Nakabayashi et al. (2016) The Journal of Nutrition.13:397S–402S

doi: 10.3945/jn.114.202317.

Comment The raw files were converted to netCDF files and stored in DROP Met as "Metabolome data in Allium plants and MS/MS spectra of S-containing compounds"


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The raw data files are available at DROP Met web site in PRIMe database of RIKEN.

Data Analysis Details Information

ID DS1
Title Data analysis
Description MS and MS/MS spectra were recorded by using Hystar 3.0 software (Bruker Daltonik). Data were processed by using DataAnalysis 4.0 (Bruker Daltonik). The raw files were converted to netCDF (named HIFI_004 for A. sativum, 006 for A. fistulosum, and 008 for A. cepa). Peak selection was performed by using the theoretical mass difference (1.99579 ± 0.001 Da) between 32S-monoisotopic ions and their 34S-substituted counterparts and natural abundance of 34S (4.29 ± 5%). S-ions were extracted under the following conditions: mass tolerance, <1 mDa; retention time, 1–15 min. Signal intensity values of all ions were divided by the signal intensity value of the internal standard lidocaine for normalization. To obtain S-ions with redundant signal intensity, ions with an intensity <0.1 were eliminated. Peak alignment was conducted by using Progenesis CoMet (Nonlinear Dynamics). The software MeV 4.8 (http://www.tm4.org/mev.html) was used for hierarchical cluster analysis. Pearson's correlation analysis was used in this analysis. The elemental composition was calculated by using SmartFormula (Bruker Daltonik) with the following limiting conditions: <1 ppm; C0−50H0−100N0−5O0−50S0−5; charge, 1.
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