New instrumentation based on the combination of electrospray ionization (ESI) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry has been developed for the study of large biomolecules. The high resolution and accurate mass measurement possible with this instrumentation are demonstrated by application of the hetereogeneous glycoprotein, Ribonuclease B (RNase B). The high resolution routinely attainable allows unambiguous charge state assignments, and thus, precise mass determination for all ions observed and demonstrates the utility of ESI-FTICR for the analysis of complex biological mixtures. In addition, results are presented for the dissociation of RNase B in both the electrospray source and in the ICR cell. The results show that phosphate adducts to RNase B molecular ions are most readily dissociated in the heated capillary inlet, less effectively by collisional activation in the 1–10 Torr capillary-skimmer region, and with significantly reduced efficiency by collisional activation in the ICR cell, where other dissociation processes dominate. This trend is correlated with the extent of molecular ion solvation expected in the three regions, and suggests that phosphate adduct removal is most effective for solvated molecular ions.

Fourier trasform ion cyclotron resonance (FTICR) mass spectrometry time domain signals from multiply charged biopolymer ions exhibit characteristics and predictable beat patterns due to the closely spaced cyclotron frequencies of the various isotopic constituents. Isotope beat frequencies can readily and accurately be predicted from the difference in cyclotron frequencies of neighbouring isotope peaks. The nature of these signals has important implications for high resolution mass analysis, particularly in instances where rapid spectral acquisition is desirable as with on-line analysis of chromatographic/electrophoretic effluents. Due to the pulsed nature of the frequency information in these transients, resolution improvements are effectively realized in a stepwise nature. As will be demonstrated, the application of apodization functions can have deleterious effects on signal-to-note and resolution when beats are present only near the beginning and end of the transient. Additionally, in instances where the length of FTICR data acquisition is critical (such as in conjunction with on-line separations or in the analysis of very high molecular weight species), it is crucial to choose data acquisition parameters based on the predicted behavior of the time domain signal for the efficient and accurate acquisition of mass spectra.

In this article, we briefly highlight the use of capillary electrophoresis for sampling, manipulating, and separating extremely small sample sizes. The extraordinary sensitivity that can be obtained by combined capillary electrophoresis-mass spectrometry is then demonstrated using recent results. We briefly describe the ability to detect noncovalently associated complexes (e.g., double-stranded DNA) by electrospray ionization-mass spectrometry, and conclude with recent results that show the potential for using high-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry for characterization of biomolecules.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTObservation of a small oligonucleotide duplex by electrospray ionization mass spectrometryK. J. Light-Wahl, D. L. Springer, B. E. Winger, C. G. Edmonds, D. G. Camp II, B. D. Thrall, and R. D. SmithCite this: J. Am. Chem. Soc. 1993, 115, 2, 803–804Publication Date (Print):January 1, 1993Publication History Published online1 May 2002Published inissue 1 January 1993https://pubs.acs.org/doi/10.1021/ja00055a070https://doi.org/10.1021/ja00055a070research-articleACS PublicationsRequest reuse permissionsArticle Views329Altmetric-Citations139LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTObservation of the multimeric forms of concanavalin A by electrospray ionization mass spectrometryK. J. Light-Wahl, B. E. Winger, and R. D. SmithCite this: J. Am. Chem. Soc. 1993, 115, 13, 5869–5870Publication Date (Print):June 1, 1993Publication History Published online1 May 2002Published inissue 1 June 1993https://doi.org/10.1021/ja00066a083RIGHTS & PERMISSIONSArticle Views376Altmetric-Citations50LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (280 KB) Get e-Alertsclose Get e-Alerts

The occurrence of small shifts in the cyclotron frequency during the acquisition of very long transients (in excess of 80 s) has been observed to be a limiting factor for ultrahigh-resolution mass measurements of protein ions performed with electrospray-ionization Fourier-transform ion-cyclotron-resonance mass spectrometry. Resolution measurements were restricted to values less than 10(6) because of the frequency shifts. Measurements of the frequency shifts, performed by sequentially transforming small segments of the transient, allowed the shift to be characterized and fitted to a 4th-order equation. The sampling rate of the acquired transient was then modulated (at a rate equal to the reciprocal of the rate for the frequency shift) to allow ultrahigh resolution, greater than 2 X 10(6), and improved mass measurement and precision to be achieved for a small protein.

The 'softness' of the electrospray ionization (ESI) method provides a direct link between solution chemistry and the inherent gas-phase environment of mass spectrometry. Available results related to the preservation of non-covalent associations into the gas phase after ESI are reviewed. These associations include the possible retention of elements of higher order protein structure, non-covalent polypeptide-heme associations and enzyme complexes. Experimental results are presented showing that non-covalently bound polypeptide and protein dimer ions are relatively common as low level contributions to ESI mass spectra. It is argued that these dimers are reflective of multimeric species in solution since Coulombic barriers preclude dimerization after ESI, although uncertainty remains regarding whether they exist prior to the formation of highly charged droplets. The dissociation of dimers is facile, and for proteins can yield monomers having a broad distribution of charge states. The detection of non-covalently associated dimers requires gentle ESI mass spectrometer interface conditions, yielding relatively low levels of internal excitation. Under such conditions, incomplete molecular ion desolvation can result in experimental artifacts for tandem mass spectrometric experiments. ESI mass spectrometry may have broad potential for the study of noncovalent liquid phase associations.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProbing qualitative conformation differences of multiply protonated gas-phase proteins via hydrogen/deuterium isotopic exchange with water-d2B. E. Winger, K. J. Light-Wahl, A. L. Rockwood, and R. D. SmithCite this: J. Am. Chem. Soc. 1992, 114, 14, 5897–5898Publication Date (Print):July 1, 1992Publication History Published online1 May 2002Published inissue 1 July 1992https://doi.org/10.1021/ja00040a084RIGHTS & PERMISSIONSArticle Views313Altmetric-Citations160LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (324 KB) Get e-Alerts Get e-Alerts