Research Article
Characterization of intrinsically disordered proteins with electrospray ionization mass spectrometry: Conformational heterogeneity of α-synuclein
Agya K. Frimpong,
Rinat R. Abzalimov,
Vladimir N. Uversky,
Igor A. Kaltashov,
Agya K. Frimpong
Department of Chemistry, University of Massachusetts Amherst, Amherst, MA
Search for more papers by this authorRinat R. Abzalimov
Department of Chemistry, University of Massachusetts Amherst, Amherst, MA
Search for more papers by this authorVladimir N. Uversky
Institute for Intrinsically Disordered Protein Research, Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN
Institute for Biological Instrumentation, Russian Academy of Sciences, Pushkino, Russia
Search for more papers by this authorCorresponding Author
Igor A. Kaltashov
Department of Chemistry, University of Massachusetts Amherst, Amherst, MA
Department of Chemistry, University of Massachusetts-Amherst, 710 North Pleasant Street, Lederle Graduate Research Tower 701, Amherst, MA 01003===Search for more papers by this authorAgya K. Frimpong,
Rinat R. Abzalimov,
Vladimir N. Uversky,
Igor A. Kaltashov,
Agya K. Frimpong
Department of Chemistry, University of Massachusetts Amherst, Amherst, MA
Search for more papers by this authorRinat R. Abzalimov
Department of Chemistry, University of Massachusetts Amherst, Amherst, MA
Search for more papers by this authorVladimir N. Uversky
Institute for Intrinsically Disordered Protein Research, Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN
Institute for Biological Instrumentation, Russian Academy of Sciences, Pushkino, Russia
Search for more papers by this authorCorresponding Author
Igor A. Kaltashov
Department of Chemistry, University of Massachusetts Amherst, Amherst, MA
Department of Chemistry, University of Massachusetts-Amherst, 710 North Pleasant Street, Lederle Graduate Research Tower 701, Amherst, MA 01003===Search for more papers by this authorAbstract
Conformational heterogeneity of α-synuclein was studied with electrospray ionization mass spectrometry by analyzing protein ion charge state distributions, where the extent of multiple charging reflects compactness of the protein conformations in solution. Although α-synuclein lacks a single well-defined structure under physiological conditions, it was found to sample four distinct conformational states, ranging from a highly structured one to a random coil. The compact highly structured state of α-synuclein is present across the entire range of conditions tested (pH ranging from 2.5 to 10, alcohol content from 0% to 60%), but is particularly abundant in acidic solutions. The only other protein state populated in acidic solutions is a partially folded intermediate state lacking stable tertiary structure. Another, more compact intermediate state is induced by significant amounts of ethanol used as a co-solvent and appears to represent a partially folded conformation with high β-sheet content. Protein dimerization is observed throughout the entire range of conditions tested, although only acidic solutions favor formation of highly structured dimers of α-synuclein. These dimers are likely to present the earliest stages in protein aggregation leading to globular oligomers and, subsequently, protofibrils. Proteins 2010. © 2009 Wiley-Liss, Inc.
Supporting Information
Additional Supporting Information may be found in the online version of this article.
| Filename | Description |
|---|---|
| PROT_22604_sm_suppinfo.pdf109.5 KB | Details of chemometric processing of the set of α-synuclein ESI MS data |
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