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Gaseous conformational structures of cytochrome c

Publication ,  Journal Article
McLafferty, FW; Guan, Z; Haupts, U; Wood, TD; Kelleher, NL
Published in: Journal of the American Chemical Society
May 20, 1998

Solution folding of a protein removes major sections of it from their aqueous environment. Complete removal, by forming water-free gaseous protein ions with electrospray ionization/mass spectrometry, profoundly changes the conformation of cytochrome c. Of these ions' exchangeable hydrogen atoms, gaseous D2O replaces 30% to 70% in distinct values indicative of at least six conformational states. Although this is increased to >95% by colliding ions with D2O, colliding instead with N2 and subsequent D2O exposure gives the same H/D exchange values, although in different proportions; on solvent removal, denatured ions spontaneously refold. Deuterated State I, II, and V ions of a range of charge values up to 17+ when charge stripped to 9+ ions do not fold appreciably, even though their cross section decreases by 20%, confirming that each has a characteristic conformational structure insensitive to electrostatic repulsion; the charge solvation of an added protonated side chain also protects additional exchangeable sites. Dramatic temperature effects on H/D exchange also support unique State I, II, IV, and V conformers with a variety of charge values. Despite extensive H/D scrambling, dissociation to locate D sites of State I, II, IV, and V ions indicates that four small α-helical regions are maintained even in the most open ionic conformations; these regions are consistent with salt bridge stabilization. In the more open conformers the α-helical regions could be partially converted to either β-sheet or denatured structures. No close similarities were found between the gaseous conformer structures and those in solution, a cautionary note for the use of ESI/MS gas- phase data to characterize noncovalent interactions in solution.

Duke Scholars

Published In

Journal of the American Chemical Society

DOI

ISSN

0002-7863

Publication Date

May 20, 1998

Volume

120

Issue

19

Start / End Page

4732 / 4740

Related Subject Headings

  • General Chemistry
  • 03 Chemical Sciences
 

Citation

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McLafferty, F. W., Guan, Z., Haupts, U., Wood, T. D., & Kelleher, N. L. (1998). Gaseous conformational structures of cytochrome c. Journal of the American Chemical Society, 120(19), 4732–4740. https://doi.org/10.1021/ja9728076
McLafferty, F. W., Z. Guan, U. Haupts, T. D. Wood, and N. L. Kelleher. “Gaseous conformational structures of cytochrome c.” Journal of the American Chemical Society 120, no. 19 (May 20, 1998): 4732–40. https://doi.org/10.1021/ja9728076.
McLafferty FW, Guan Z, Haupts U, Wood TD, Kelleher NL. Gaseous conformational structures of cytochrome c. Journal of the American Chemical Society. 1998 May 20;120(19):4732–40.
McLafferty, F. W., et al. “Gaseous conformational structures of cytochrome c.” Journal of the American Chemical Society, vol. 120, no. 19, May 1998, pp. 4732–40. Scopus, doi:10.1021/ja9728076.
McLafferty FW, Guan Z, Haupts U, Wood TD, Kelleher NL. Gaseous conformational structures of cytochrome c. Journal of the American Chemical Society. 1998 May 20;120(19):4732–4740.
Journal cover image

Published In

Journal of the American Chemical Society

DOI

ISSN

0002-7863

Publication Date

May 20, 1998

Volume

120

Issue

19

Start / End Page

4732 / 4740

Related Subject Headings

  • General Chemistry
  • 03 Chemical Sciences