@article {2309,
	title = {Conformations of Gas-Phase Ions of Ubiquitin, Cytochrome c, Apomyoglobin, and beta-Lactoglobulin Produced from Two Different Solution Conformations},
	journal = {Journal of the American Society for Mass Spectrometry},
	volume = {19},
	number = {12},
	year = {2008},
	note = {ISI Document Delivery No.: 385IWTimes Cited: 2Cited Reference Count: 36Wright, P. John Zhang, Jianmin Douglas, D. J.},
	month = {Dec},
	pages = {1906-1913},
	type = {Article},
	abstract = {At low pH in solutions of 50\% methanol, proteins form expanded denatured states (the "H" state). In 90\% methanol, proteins form expanded helical denatured states with artificial alpha-helices (the "H-c" state). Gas-phase ions of ubiquitin, cytochrome c, apomyoglobin, and native and disulfide-reduced beta-lactoglobulin were formed by electrospray ionization (EST) of the proteins from the H and H-c states in solution. Both states in solution produce the same charge states in EST. The conformations of the ions were studied with cross section measurements and gas-phase H/D exchange experiments. The cross sections show that the ions retain considerable folded structure. For a given protein and given charge state, ions produced from the H and H-c states showed the same cross sections (within similar to 1\%). Ions of cytochrome c, apomyoglobin, and native and reduced beta-lactoglobulin of a given charge state showed no differences in H/D exchange level when produced from the H or H-c state. However, ubiquitin ions produced from the H-c state consistently exchange fewer (similar to 13\%) hydrogens than ions produced from the H state, suggesting that in this case the gas-phase protein ions retain some memory of their solution conformations. (J Am Soc Mass Spectrom 2008, 19, 1906-1913) (c) 2008 Published by Elsevier Inc. on behalf of American Society for Mass Spectrometry},
	keywords = {CIRCULAR-DICHROISM, COLLISION CROSS-SECTIONS, H/D EXCHANGE, HYDROGEN/DEUTERIUM EXCHANGE, IONIZATION MASS-SPECTROMETRY, MYOGLOBIN, OF-FLIGHT, PROTEIN IONS, STABILITY, SYSTEM, TRAP},
	isbn = {1044-0305},
	url = {<Go to ISI>://000261808900023},
	author = {Wright, P. J. and Zhang, J. M. and Douglas, D. J.}
}
@article {1097,
	title = {Linear ion traps in mass spectrometry},
	journal = {Mass Spectrometry Reviews},
	volume = {24},
	number = {1},
	year = {2005},
	note = {ISI Document Delivery No.: 888OJTimes Cited: 73Cited Reference Count: 145},
	month = {Jan-Feb},
	pages = {1-29},
	type = {Review},
	abstract = {Linear ion traps are finding new applications in many areas of mass spectrometry. In a linear ion trap, ions are confined radially by a two-dimensional (2D) radio frequency (RF) field, and axially by stopping potentials applied to end electrodes. This review focuses on linear ion trap instrumentation. Potentials and ion motion in linear multipole fields and methods of ion trapping, cooling, excitation, and isolation are described. This is followed by a description of various mass discrimination effects that have been reported with linear ion traps. Linear ion traps combined in various ways with three-dimensional (3D) traps, time-of-flight (TOF) mass analyzers, and Fourier transform ion cyclotron resonance mass spectrometers are then given. Linear ion traps can be used as stand alone mass analyzers, and their use for mass analysis by Fourier transforming image currents, by mass selective radial ejection, and by mass selective axial ejection are reviewed. (C) 2004 Wiley Periodicals, Inc.},
	keywords = {analysis, CYCLOTRON-RESONANCE, ELECTROSPRAY-IONIZATION, EXCITATION, EXTERNAL ACCUMULATION, FRINGING FIELDS, INVERSE FOURIER-TRANSFORM, ion traps, linear multipoles, mass, MOLECULE REACTION, OCTOPOLE FIELDS, OF-FLIGHT, QUADRUPOLE, RADIOFREQUENCY, RESONANCE, space charge, STORAGE ASSISTED DISSOCIATION, SYSTEM},
	isbn = {0277-7037},
	url = {<Go to ISI>://000226383800001},
	author = {Douglas, D. J. and Frank, A. J. and Mao, D. M.}
}
@article {439,
	title = {Hydrogen/deuterium exchange of myoglobin ions in a linear quadrupole ion trap},
	journal = {Rapid Communications in Mass Spectrometry},
	volume = {16},
	number = {20},
	year = {2002},
	note = {ISI Document Delivery No.: 604ADTimes Cited: 10Cited Reference Count: 26},
	pages = {1941-1945},
	type = {Article},
	abstract = {The hydrogen/deuterium (H/D) exchange of gas-phase ions of holo- and apo-myoglobin has been studied by confining the ions in a linear quadrupole ion trap with D2O or CD3OD at a pressure of several mTorr. Apo-myoglobin ions were formed by collision-induced dissociation of holomyoglobin ions between the orifice and skimmer of the ion sampling system. The exchange takes place on a time scale of seconds. Earlier cross section measurements have shown that holomyoglobin ions can have more compact structures than apo-myoglobin. Despite this, both holomyoglobin and apo-myoglobin in charge states +8 to +14 are found to exchange nearly the same number of hydrogens (ca. 103) in 4 s. It is possible the ions fold or unfold to new conformations on the much longer time scale of the exchange experiment compared with the cross section measurements. Copyright (C) 2002 John Wiley Sons, Ltd.},
	keywords = {COLLISION CROSS-SECTIONS, CYTOCHROME-C, GAS-PHASE, HEME, HOLOMYOGLOBIN, HYDROGEN-DEUTERIUM EXCHANGE, MASS-SPECTROMETRY, OF-FLIGHT, PROTEIN IONS, STABILITY, SYSTEM},
	isbn = {0951-4198},
	url = {<Go to ISI>://000178592700007},
	author = {Mao, D. M. and Ding, C. F. and Douglas, D. J.}
}
