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Metabolomics in Focus
Welcome to the Daltonics Dispatch, a resource from Bruker Daltonics highlighting the application of mass spectrometry technologies to provide answers to analytical questions that confront our customers everyday. At Bruker Daltonics, we’re proud to be a leader in providing Mass Spectrometry solutions. We are committed to earning our reputation for outstanding performance, superior quality, and excellent service and support. To that end, we’ve developed the Dispatch as a platform to illustrate, through short papers and editorial pieces, how our various mass spec technologies are being applied to applications in laboratories around the world. Each issue will focus on an application area and will be highlighted by examples of how researchers are utilizing our mass spectrometry systems to effectively answer analytical questions. We’ve created the Dispatch as a vehicle for you to learn and benefit from the results and experiences of others who successfully overcame challenges. We hope you will be inspired by their success. This is your newsletter-so please help us make it work for you! E-mail us at dispatch@bdal.de. with your ideas, submission, or comments We hope you enjoy the Dispatch!
For the identification and especially the differentiation of structural isomeric compounds MSn is often mandatory, making ion trap systems the instrument of choice. Here we present new developments implemented with the amaZon speed system enabling fast and efficient MSn analysis compatible with modern UHPLC and resulting in reproducible, high quality fragmentation spectra .
In this study we profiled metabolite extracts of wild type and mutant Arabidopsis thaliana seedlings impaired in flavonoid biosynthesis. Multivariate data analysis revealed that several compounds were absent in the mutant strains. MS/MS and Pseudo-MS³ data acquired on a maXis impact high-resolution Q-TOF instrument enabled unambiguous elemental composition determination for precursor and fragment ions. Correlating this information with hypothetical compound structures using the FragmentExplorer™ enabled the tentative identification of a flavonoid-glucoside: quercetin- 3-O-rhamnoside-7-O-glucoside. The aglycon structure could be verified by comparing Pseudo-MS³ spectra with reference spectra of a quercetin standard. Interestingly, querying an MS/MS library that was measured on a micrOTOF-Q with the quercetin aglycon Pseudo-MS³ spectrum measured on the maXis impact returned the same candidate hit. This result demonstrates the applicability of shared MS/MS data acquired on different Q-TOF instruments – even in different labs – for fast de-replication workflows.
Because known pathogens become increasingly resistant to antibiotics, and at the same time, new threats to human health emerge, there is a constant need for the discovery of novel natural products. Microorganisms have a longstanding tradition as a source of biologically active small molecules – termed “secondary metabolites“ – and in addition to well-known producers like the actinomycetes, new sources have been established. We describe here the application of LC-MS and LC-NMR techniques for the discovery and structural elucidation of novel natural products from myxobacteria. These soilliving bacteria exhibit outstanding biological characteristics such as cooperative swarming on surfaces and formation of multicellular fruiting bodies (Fig. 1). In addition, many myxobacterial strains are also producers of secondary metabolites exhibiting a wide range of biological activities [1] – examples include the antibacterial thuggacins, antifungal compounds like ambruticin and the cytotoxic epothilones.
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Protein substrates of a novel secretion system of Porphyromonas gingivalis contain a conserved C-terminal domain (CTD) essential for secretion and attachment to the cell surface. Inactivation of lptO (PG0027) or porT produced mutants that lacked surface protease activity and an electron-dense surface layer. Both mutants showed co-accumulation of A-LPS and unmodified CTD proteins in the periplasm. Lipid profiling by mass spectrometry showed the presence of both tetra- and penta-acylated forms of mono-phosphorylated lipid A in the wild-type and porT mutant, while only the penta-acylated forms of mono-phosphorylated lipid A were found in the lptO mutant, indicating a specific role of LptO in the O-deacylation of mono-phosphorylated lipid A. Increased levels of non-phosphorylated lipid A and the presence of novel phospholipids in the lptO mutant were also observed that may compensate for the missing mono-phosphorylated tetra-acylated lipid A in the outer membrane (OM). Molecular modelling predicted LptO to adopt a β-barrel structure characteristic of an OM protein, supported by the enrichment of LptO in OM vesicles. The results suggest that LPS deacylation by LptO is linked to the co-ordinated secretion of A-LPS and CTD proteins by a novel secretion and attachment system to form a structured surface layer.
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This study describes a highly efficient method for the selective precipitation of phosphoproteins by trivalent europium-, terbium-, and erbium metal ions. These metal cations belong to the group of lanthanides and are known to be hard “acceptors” with an overwhelming preference for oxygen-containing anions such as phosphates to which they form very tight ionic bonds. The method could be successfully applied to specifically precipitate phosphoproteins from complex samples including milk and egg-white by forming solid metal-protein complexes. Due to the low solubility product of the investigated lanthanide salts, the produced metal-protein complexes showed high stability. The protein pellets were extensively washed to remove non-phosphorylated proteins and contaminants. For the analysis of proteins the pellets were first dissolved in 30% formic acid and subjected to MALDI-TOF MS. For peptide mass-fingerprint analysis the precipitated phosphoproteins were enzymatically digested using microwave-assisted digestion. The method was found to be highly specific for the isolation and purification of phosphoproteins. Protein quantification was performed by colorimetric detection of total precipitated phosphoproteins and revealed more than 95% protein recovery for each lanthanide salt.
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Bruker has developed a high quality pesticide screening application in conjunction with laboratories in the industry. Currently with over 650 compounds in the library and a runtime as short as 10 minutes, the Pesticide Screener offers some unique capabilities. Utilising the accurate mass capabilities of the microTOF Q II mass spectrometer, coupled to UHPLC, high sensitivity and very high identification confidence is achieved. Compound identification is further enhanced by the introduction of orthogonal data, for example, True Isotopic Pattern fitting, accurate mass MS and MS/MS, retention time and the use of qualifier ions. Finally the use of Bruker Q-TOF technology allows for retrospective screening of data. This opens up an opportunity to look for things that were not on your agenda yesterday.
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