SE157:/MS3

Sample Set Information

ID	TSE1313
Title	Top-down Metabolomic Approaches for Nitrogen-Containing Metabolites.
Description	Streamlining the processes that reveal heteroatom-containing metabolites and their biosynthetic genes is essential in integrated metabolomics studies. These metabolites are especially targeted for their potential pharmaceutical activities. By using a Fourier-transform ion cyclotron resonance-mass spectrometry (FTICR-MS) instrument, we provide top-down targeted metabolomic analyses using ultrahigh-resolution liquid chromatography-mass spectrometry (LC-MS), high-resolution matrix-assisted laser desorption/ionization (MALDI), and high-resolution imaging mass spectrometry (IMS) with 15N labeling of nitrogen-containing metabolites. In this study, we efficiently extract known and unknown chemicals and spatial information from the medicinal plant Catharanthus roseus, which sources several cancer drugs. The ultrahigh-resolution LC-MS analysis showed that the molecular formula of 65 N-metabolites were identified using the petals, peduncles, leaves, petioles, stems, and roots of the non- and 15N-labeled Catharanthus plants. The high resolution MALDI analysis showed the molecular formula of 64 N-metabolites using the petals, leaves, and stems of the non- and 15N-labeled Catharanthus. The chemical assignments using molecular formulas stored in databases identified known and unknown metabolites. The comparative analyses using the assigned metabolites revealed that most of the organ-specific ions are derived from unknown N-metabolites. The high-resolution IMS analysis characterized the spatial accumulation patterns of 32 N-metabolites using the buds, leaves, stems, and roots in Catharanthus. The comparative analysis using the non- and 15N-labeled IMS data showed the same spatial accumulation patterns of a non- and 15N-labeled metabolite in the organs, showing that top-down analysis can be performed even in IMS analysis.
Authors	Nakabayashi R, Hashimoto K, Toyooka K, Saito K.
Reference	Anal Chem. 2017 Mar 7;89(5):2698-2703. doi: 10.1021/acs.analchem.6b04163. Epub 2017 Feb 22.
Comment

PubMed

Analytical Method Details Information

ID	MS3
Title	IMS (MALDI)
Instrument	MS FTICR–MS solariX 7.0 T (Bruker Daltonics)
Instrument Type
Ionization	ESI
Ion Mode	Positive
Description	Preparation of Frozen Section Fresh tissues were cut about 5 mm with a razor, embedded with a compound (Surgipath FSC22: Leica Microsystems, Germany) and frozen in a −75 °C acetone bath (Histo-Tek Pino: Sakura Finetek Japan Co.,Ltd., Tokyo, Japan). The frozen samples were placed on the cryostat specimen disk and cut with the knife blade until the desired tissue is exposed. The face of the frozen sample was put on the adhesive film (Kawamoto’s film method) at 16μm thickness in a cryostat (CM3050S, Leica Microsystems, Germany). The section on the film was freeze-dried overnight at −30 °C in the cryostat (Figure S9 in the Supporting Information). For light microscopy, the frozen sections were stained with 0.05% toluidine-blue O solution for a minute and then washed with distilled water. IMS Analysis The freeze-dried section on the film was attached to a glass slide (ITO coating, Bruker Daltonik GmbH) with cellophane tape. The CHCA matrix solution (7 mg/mL 80% MeOH including 0.2% TFA) was sprayed onto the glass slide using ImagePrep (Bruker Daltonik GmbH) set to the default parameters. The freeze-dried section with the matrix was analyzed in the FTICR–MS instrument using the MALDI source. The analytical conditions were as follows. MALDI control: geometry, MTP 384 ground steel; plate offset, 100.0 V; deflector plate, 200.0 V; laser power, 30.00%; laser shots, 200; frequency, 2000 Hz; laser focus, small; raster width, 30 μm. The analytical conditions of MALDI in the IMS analysis were identical to those described in the MALDI analysis.
Comment_of_details