Coupling mass spectrometers in series provides a new technique that has many advantages for the analysis of specific organic compounds in complex mixtures. Sensitivity to picograms of targeted compounds can be achieved with high specificity and nearly instantaneous response. The targeted compound is selectively ionized, and its characteristic ions are… (More)
Electrospray ionization with an ultralow flow rate (</=4 nanoliters per minute) was used to directly couple capillary electrophoresis with tandem mass spectrometry for the analysis and identification of biomolecules in mixtures. A Fourier transform mass spectrometer provided full spectra (>30 kilodaltons) at a resolving power of approximately 60,000 for… (More)
For characterization of sequence and posttranslational modifications, molecular and fragment ion mass data from ionizing and dissociating a protein in the mass spectrometer are far more specific than are masses of peptides from the protein's digestion. We extend the approximately 500-residue, approximately 50-kilodalton (kD) dissociation limitation of this… (More)
The structural evolution of ubiquitin after transfer into the gas phase was studied by electron capture dissociation. Site-specific fragment yields show that ubiquitin's solution fold is overall unstable in the gas phase, but unfolding caused by loss of solvent is slowest in regions stabilized by salt bridges.
Automation of the interpretation of unknown mass spectra is a necessity in many laboratories. Two types of computer programs have been developed for this; "retrieval systems compare the unknown against a file of reference spectra, while interpretation' programs identify various molecular features to aid the interpreter. Particular emphasis here will be… (More)
A recently developed methodology for the characterization of complex proteomes, top-down Fourier transform mass spectrometry (FTMS), is applied for the first time to a plant proteome, that of the model plant Arabidopsis thaliana. Of the 3000 proteins predicted by the genome sequence, 97 were recently identified in two separate "bottom-up" mass spectrometry… (More)
Reactive or unstable molecules are key intermediates in many important reactions, but can be difficult to prepare for experimental studies. Species with missing (:CH-OH) or extra (H3) substituents can often be formed conveniently in the gas phase by neutralizing a beam of a more stable ionic counterpart (CH = O+H, H3+). Reionization of the neutral after… (More)
Sir: Plasma desorption (PD), such as that induced by the 100-MeV fission products of z5zCf, is a particularly promising ionization method for large molecules (1-5), yielding molecular inn species even from trypsin, molecular weight 23463. Further, with trypsin using nitrocellulose as the substrate, (M + 3H)3+ is the most abundant molecular ion species and… (More)