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Titolo:
GASEOUS CONFORMATIONAL STRUCTURES OF CYTOCHROME-C
Autore:
MCLAFFERTY FW; GUAN ZQ; HAUPTS U; WOOD TD; KELLEHER NL;
Indirizzi:
CORNELL UNIV,BAKER LAB,DEPT CHEM ITHACA NY 14853
Titolo Testata:
Journal of the American Chemical Society
fascicolo: 19, volume: 120, anno: 1998,
pagine: 4732 - 4740
SICI:
0002-7863(1998)120:19<4732:GCSOC>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
RESONANCE MASS-SPECTROMETRY; MULTIPLY-CHARGED IONS; INFRARED MULTIPHOTON DISSOCIATION; GAS-PHASE; ELECTROSPRAY-IONIZATION; QUADRUPOLAR EXCITATION; RADIATIVE DISSOCIATION; PROTEIN IONS; AXIALIZATION; DENATURATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
67
Recensione:
Indirizzi per estratti:
Citazione:
F.W. Mclafferty et al., "GASEOUS CONFORMATIONAL STRUCTURES OF CYTOCHROME-C", Journal of the American Chemical Society, 120(19), 1998, pp. 4732-4740

Abstract

Solution folding of a protein removes major sections of it from theiraqueous 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% bp colliding ions with D2O, colliding instead with N-2 and subsequent D2O exposure gives the same H/D exchange values, although in different proportions; on solvent removal, denatured ions spontaneously refold. Deuterated Slate I, II, and V ions of a range of chargeValues up to 17+ when charge stripped to 9+ ions do nor fold appreciably, even though their cross section decreases by 20%, confirming thateach has a characteristic conformational structure insensitive to electrostatic repulsion; the charge solvation of an added protonated sidechain 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, N, and V ions indicates that four small alpha-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 alpha-helicalregions could be partially converted to either beta-sheet or denatured structures. No close similarities were found between the gaseous conformer structures and those in solution, a cautionary note for the useof ESI/MS gas-phase data to characterize noncovalent interactions in solution.

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Documento generato il 09/07/20 alle ore 21:47:28