Introduction

METLIN is a metabolite database for metabolomics containing over 15,000 structures, it is also represents a data management system designed to assist in a broad array of metabolite research and metabolite identification by providing public access to its repository of current and comprehensive mass spectral metabolite data.

News/Updates

Both Metlin and XCMS are updated on a monthly basis. For more information on XCMS please visit the XCMS page at http://masspec.scripps.edu/xcms/

Database

Metabolite Data: An annotated list of known metabolites and their mass, chemical formula, and structure is readily available on the METLIN website. Each metabolite is conveniently linked to outside resources such as the the Kyoto Encyclopedia of Genes and Genomes (KEGG) for further reference and inquiry. A user platform for cross-correlation between metabolite data and spectra data from LC/MS (liquid chromatography-mass spectrometry) and FTMS (Fourier Transform Mass Spectrometry) is included. The list is expanding continuously as more metabolite information is being deposited and discovered.

FTMS Data: High-resolution FTMS spectra from a number of chromatographically separated human serum fractions is stored in the database. Additional FTMS datasets from other biofluids and tissues are also present. Accurate mass measurement and isotopic pattern evaluation from FTMS datasets are especially helpful in metabolite characterization and identification.

LC/MS Data: This reference LC/MS data currently catalogues a diverse set of LC/MS profiles from tissues and biofluids. The purpose of this information is simply to provide reference data from diverse sample sources yet is not meant for quantitative comparisons. The biofluid/tissue properties (e.g., source, preparation, and derivatization method) and analytical variables (e.g., chromatography, instrument type and ionization mode) associated with each sample are tracked to allow for individualized queries.

Searches

METLIN allows for customizable searches of metabolite data based on user-selected parameters, including, but not limited to, biofluid type, disease, gender, and age. Also available are chemical substructure and similarity searches. Users may limit their searches to a specific mass and retention range. Approximately 400-1200 LC/MS peaks are externally generated for every biological sample. For further local analysis, identified peak lists from each dataset can be downloaded from the website. To aid users, search results can be visualized with plotting options that include colorized 3-dimensional LC/MS plots, scatter plots and histograms, with the added feature of color-coding of mass values based on different parameters.

Statistics

LC/MS Analyses:	216
Metabolites:	23216
Metabolite MS/MS Spectra:Positive Mode	451
Negative Mode:	371
Total Metabolites with MSMS	615
Total MSMS spectra:	3288

Credits

The METLIN Metabolite Database is a collaborative effort between the Abagyan Group and the Center for Mass Spectrometry at The Scripps Research Institute.