Direct Introduction of Biological Samples into a LTQ-Orbitrap Hybrid Mass Spectrometer as a Tool for Fast Metabolome Analysis

Abstract

We report the direct introduction of biological samples into a high-resolution mass spectrometer, the LTQ-Orbitrap, as a fast tool for metabolomic studies. A proof of concept study was performed on yeast cell extracts that were introduced into the mass spectrometer by using flow injection analysis, with an acquisition time of 3 min. Typical mass spectra contained a few thousand m/z signals, 400 of which were found to be analytically relevant (i.e., their intensity was 3-fold higher than that of the background noise and they occurred in at least 60% of the acquisition profiles under identical experimental conditions). The method was validated by studies of the matrix effect, linearity, and intra-assay precision. Accurate mass measurements in the Orbitrap discriminated between isobaric ions and also indicated the elemental composition of the ions of interest with mass errors below 5 ppm, for identification purposes. The proposed structures were then assessed by MSn experiments via the linear ion trap, together with accurate mass determination of the product ions in the Orbitrap analyzer. When applied to the study of cadmium toxicity, the method was as effective as that initially developed by using LC/ESI-MS/MS for a targeted approach. The same metabolic fingerprints were also subjected to multivariate statistical analyses. The results highlighted a reorganization of amino acid metabolism under cadmium conditions in order to increase the biosynthesis of glutathione.

Exploring metallodrug–protein interactions by mass spectrometry: comparisons between platinum coordination complexes and an organometallic ruthenium compound

“…High-resolution ESI MS has previously been used to study covalent and non-covalent ligand-biomolecule interactions [37,38] and to screen complex mixtures of metabolites [39][40][41], often without the need for chromatographic separation of the adducts prior to analysis. Hence, this method allows the simultaneous screening of complicated mixtures of compounds with the direct (Ub), cytochrome c (cyt c) and superoxide dismutase (SOD) (1:1:1) in tetramethylammonium acetate (TMeAmAc) buffer pH 7.4 and the same protein mixture after 24-h incubation at 37°C with cisplatin, transplatin and RAPTA-C, respectively (5:1 metal-to-protein ratio).…”

Dug1p Is a Cys-Gly Peptidase of the γ-Glutamyl Cycle of Saccharomyces cerevisiae and Represents a Novel Family of Cys-Gly Peptidases

“…It is a fast and reliable tool that has been successfully applied earlier to investigate the metabolic response of S. cerevisiae to cadmium exposure (28). Typical yeast mass spectra contain a few hundred analytically relevant m/z signals.…”

“…The procedure has been adapted from Madalinski et al (28). Briefly, the analyses were performed by flow injection analysis by using an Accela pump and an Accela autosampler from Thermo Fisher Scientific (San Jose, CA).…”

High throughput volatile fatty acid skin metabolite profiling by thermal desorption secondary electrospray ionisation mass spectrometry

“…212.07, was present in all the samples and blanks and this was assigned to the plasticiser n-butyl benzensulfonamide, an ion that has been used previously as a lockmass in the negative ion mode [42] and was used in this study with the TD-SESI-MS data enabling the target VFAs Figure 2 to be identified with a mass accuracy of 3.5 ppm or less [43].…”