SE130:/DS1

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"

PubMed

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.
Comment_of_details