A5011247764- Mass Spectrometry Techniques and Applications
- Advanced Proteomics Techniques and Applications
- Analytical Chemistry and Chromatography
- Ion-surface interactions and analysis
- Diatoms and Algae Research
- Microbial Natural Products and Biosynthesis
- Enzyme Structure and Function
- RNA and protein synthesis mechanisms
- Glycosylation and Glycoproteins Research
- Particle accelerators and beam dynamics
- Genomics and Phylogenetic Studies
- Metabolomics and Mass Spectrometry Studies
- DNA and Nucleic Acid Chemistry
- Microfluidic and Capillary Electrophoresis Applications
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Analytical chemistry methods development
- Plant biochemistry and biosynthesis
- Geology and Paleoclimatology Research
- Porphyrin Metabolism and Disorders
- Folate and B Vitamins Research
- Aquatic Ecosystems and Phytoplankton Dynamics
- Marine Sponges and Natural Products
- Botany and Plant Ecology Studies
- Antibiotics Pharmacokinetics and Efficacy
University of Michigan
2012-2024
Uppsala University
1998-2015
Lund University
1994-2011
Division of Chemistry
2010-2011
Wellcome Centre for Human Neuroimaging
2010
King's College London
2010
Scripps Institution of Oceanography
2006-2009
University of Pittsburgh
2009
National High Magnetic Field Laboratory
2001-2004
Florida State University
2001-2004
Due to the dynamic nature and low stoichiometry of protein phosphorylation, enrichment phosphorylated peptides from proteolytic mixtures is often necessary prior their characterization by mass spectrometry. Several phosphopeptide isolation strategies have been presented in literature, including immobilized metal ion affinity chromatography. However, that technique suffers poor selectivity reproducibility. Recently, titanium dioxide-based columns successfully employed for several research...
Glycoproteins are a functionally important class of biomolecules for which structural elucidation presents challenge. Fragmentation N-glycosylated peptides, employing collisionally activated dissociation, typically yields product ions that result from dissociation at glycosidic bonds, with little occurrence peptide backbone sites. We have applied two techniques, electron capture (ECD) and infrared multiphoton (IRMPD), in 7-T Fourier transform ion cyclotron resonance mass spectrometer, the...
We have mounted a permanent on-axis dispenser cathode electron source inside the magnet bore of 9.4-T Fourier transform ion cyclotron resonance mass spectrometer. This configuration allows capture dissociation (ECD) to be performed reliably on millisecond time scale. also implemented an off-axis laser geometry that enables simultaneous access ECD and infrared multiphoton (IRMPD). Optimum performance both fragmentation techniques is maintained. The analytical utility performing either or...
In many macroorganisms, the ultimate source of potent biologically active natural products has remained elusive due to an inability identify and culture producing symbiotic microorganisms. As a model system for developing meta-omic approach characterize product pathways from invertebrate-derived microbial consortia, we chose investigate ET-743 (Yondelis) biosynthetic pathway. This molecule is approved anticancer agent obtained in low abundance (10(-4)-10(-5) % w/w) tunicate Ecteinascidia...
We have used electrospray ionization (ESI) Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry to characterize amino acid side chain losses observed during electron capture dissociation (ECD) of ten 7- 14-mer peptides. Side-chain cleavages were for arginine, histidine, asparagine or glutamine, methionine, and lysine residues. All peptides containing an glutamine showed the associated with that residue. Methionine side-chain loss was doubly-protonated bombesin. Lysine...
We extend the application of electron capture dissociation (ECD) (which requires at least two charges) to oligosaccharides without basic functionalities by utilizing alkali, alkaline earth, and transition metals (Na+, K+, Ca2+, Ba2+, Mg2+, Mn2+, Co2+, Zn2+) as charge carriers in electrospray ionization. Both linear branched were examined, including maltoheptoase, p-lacto-N-hexaose, an N-linked glycan from human α1-acid glycoprotein. For comparison, infrared multiphoton (IRMPD) was also...
The asbABCDEF gene cluster from Bacillus anthracis is responsible for biosynthesis of petrobactin, a catecholate siderophore that functions in both iron acquisition and virulence murine model anthrax. We initiated studies to determine the biosynthetic details petrobactin assembly based on mutational analysis asb operon, identification accumulated intermediates, addition exogenous siderophores mutant strains. As starting point, in-frame deletions each genes locus (asbABCDEF) were constructed....
An unexpected biochemical strategy for chain initiation is described the loading module of polyketide synthase curacin A, an anticancer lead derived from marine cyanobacterium Lyngbya majuscula . A central GCN5-related N -acetyltransferase (GNAT) domain bears bifunctional decarboxylase/ S activity, both unprecedented GNAT superfamily. CurA tridomain, consisting adaptor domain, and acyl carrier protein, was assessed biochemically, revealing that a showing homology to (GNAT L ) catalyzes (i)...
Biosynthetic innovation in natural product systems is driven by the recruitment of new genes and enzymes into these complex pathways. Here, an unprecedented decarboxylative chain termination mechanism described for polyketide synthase curacin A, anticancer lead compound isolated from marine cyanobacterium Lyngbya majuscula. The unusual module containing adjacent sulfotransferase (ST) thioesterase (TE) catalytic domains embedded CurM was biochemically characterized. TE proved to catalyze a...
Electron detachment dissociation (EDD), recently introduced by Zubarev and co-workers for the of multiply charged biomolecular anions via a radical ion intermediate, has been shown to be analogous electron capture (ECD) in several respects, including more random peptide fragmentation retention labile posttranslational modifications. We have previously demonstrated unique behavior ECD compared vibrational excitation oligodeoxynucleotide cations. However, that approach is limited poor...
This study describes the functional identification of a pair mechanistically diverse enzymes that catalyze successive dehydration (CurE ECH1) and decarboxylation (CurF ECH2) (S)-HMG-ACP to generate 3-methylcrotonyl-ACP intermediate, presumed precursor cyclopropyl ring in curacin A. The reactions catalyzed by ECH1 ECH2 are found broad cross-section microbial natural product gene clusters participate introduction carbon chain branch points group diversity as key steps HMG-CoA synthase mediated...
yr. The period AD 1300-1550 witnessed a drop in sediment yield to 0.5-1.5 ha-1 yr-1, perhaps related the agrarian depression, and recent expansion of cultivated area has led 1.5 fold increase yield. 4. Reconstructions P flux present 1682 catchments suggests that contrast highly subsidised system, earlier system ran at net loss with losses rate kg yr-'. 5. Close calibration environmental records may form basis for reconstructing processes quantifying thresholds, time-lags, response recovery...
The combination of electron capture dissociation (ECD) and infrared multiphoton (IRMPD) for the structural characterization high-mannose type glycopeptides is explored in depth first time. Contrary to previous applications other glycan types, our analyses reveal that IRMPD does not necessarily selectively induce cleavage glycopeptides; rather peptide backbone can effectively compete with glycosidic cleavage. Poor due a higher gas-phase stability mannose-linking bonds. This reasoning also...
The CurA halogenase (Hal) catalyzes a cryptic chlorination leading to cyclopropane ring formation in the synthesis of natural product curacin A. Hal belongs family enzymes that use Fe 2+ , O 2 and α-ketoglutarate (αKG) perform variety halogenation reactions biosynthesis. Crystal structures enzyme five ligand states reveal strikingly different open closed conformations dependent on αKG binding. form represents ligand-free enzyme, preventing substrate from entering active site until both...
The dynamic mechanisms by which RNAs acquire biologically functional structures are of increasing importance to the rapidly expanding fields RNA therapeutics and biotechnology. Large energy barriers separating misfolded states arising from alternate base pairing a well-appreciated characteristic RNA. In contrast, it is typically assumed that functionally folded occupies single native basin attraction free deeply dividing (ergodic hypothesis). This assumption widely used as an implicit basis...
The generation of gaseous polyanions with a Coulomb barrier has attracted attention as exemplified by previous studies fullerene dianions. However, this phenomenon not been reported for biological anions. By contrast, electron attachment to multiply charged peptide and protein cations seen surge interest due the high utility tandem mass spectrometry (MS/MS). Electron capture dissociation (ECD) transfer (ETD) involve radical-driven fragmentation charge-reduced peptide/protein yield N-C(α)...
Electron capture dissociation of the peptide Substance P is reported for first time, with an unmodified, commercially available Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. The fragmentation pattern compared that obtained collisionally induced ions in electrospray source, and note electron gives a more easily interpreted spectrum, showing mainly C-fragments. With exception proline residues, which require cleavage two chemical bonds, we observe all C-fragmental find...
Electron capture dissociation (ECD) of the peptide Substance P (SubP) complexed with divalent metals has been investigated. ECD [SubP + H M]3+ (M2+ = Mg2+ -Ba2+ and Mn2+ -Zn2+) allowed observation a larger number product ions than previous investigations doubly charged metal-containing peptides. Mg-Ba, Mn, Fe, Zn-containing complexes resulted in without metal from cleavage backbone amine bonds (c' z* -type ions). By contrast, Co Ni-containing yielded major bond cleavages within C-terminal...