@article {5004,
	title = {The methanol-induced conformational transitions of beta-lactoglobulin, cytochrome c, and ubiquitin at low pH: A study by electrospray ionization mass spectrometry},
	journal = {Journal of the American Society for Mass Spectrometry},
	volume = {12},
	number = {3},
	year = {2001},
	note = {ISI Document Delivery No.: 408WBTimes Cited: 45Cited Reference Count: 51},
	month = {Mar},
	pages = {317-328},
	type = {Article},
	abstract = {The methanol-induced conformational transitions under acidic conditions for beta -lactoglobulin, cytochrome c, and ubiquitin, representing three different classes of proteins with beta -sheets, alpha -helices, and both alpha -helices and beta -sheets, respectively, are studied under equilibrium conditions by electrospray ionization mass spectrometry (ESI-MS). The folding states of proteins in solution are monitored by the charge state distributions that they produce during ESI and by hydrogen/deuterium (H/D) exchange followed by ESI-MS. The changes in charge state distributions are correlated with earlier studies by optical and other methods which have shown that, in methanol, these proteins form partially unfolded intermediates with induced ct-helix structure. Intermediate states formed at about 35\% methanol concentration are found to give bimodal charge state distributions. The same rate of H/D exchange is shown by the two contributions to the bimodal distributions. This suggests the intermediates are highly flexible and may consist of a mixture of two or more rapidly interconverting conformers. H/D exchange of proteins followed by ESI-MS shows that helical denatured states, populated at around 50\% methanol concentration, transform into more protected structures with further increases in methanol concentration, consistent with previous circular dicroism studies. These more protected structures still produce high charge states in ESI, similar to those of the fully denatured proteins. (C) 2001 American Society for Mass Spectrometry.},
	keywords = {2-DIMENSIONAL NMR, ALPHA-HELIX, AMIDE HYDROGEN-EXCHANGE, COMPLETE SEQUENCE, DENATURED STATES, DEUTERIUM-EXCHANGE, INTERMEDIATE, MYOGLOBIN, PROTEIN, SOLVENT},
	isbn = {1044-0305},
	url = {<Go to ISI>://000167349200010},
	author = {Babu, K. R. and Moradian, A. and Douglas, D. J.}
}
@article {4726,
	title = {Methanol-induced conformations of myoglobin at pH 4.0},
	journal = {Biochemistry},
	volume = {39},
	number = {47},
	year = {2000},
	note = {ISI Document Delivery No.: 378UETimes Cited: 62Cited Reference Count: 78},
	month = {Nov},
	pages = {14702-14710},
	type = {Article},
	abstract = {The equilibrium methanol-induced conformation changes of holomyoglobin (hMb) at pH 4.0 have been studied by circular dichroism, tryptophan fluorescence, and Soret band absorption and by electrospray ionization mass spectrometry (ESI-MS). Optical spectra show the following: (1) In 35-40\% (v/v) methanol/water, the native-like secondary structure remains, the tertiary structure is lost, the heme protein interactions are decreased, and a folding intermediate is formed. (2) In 50\% methanol, heme is lost from the protein, and there is a small decrease in helicity together with a loss of tertiary structure. (3) At > 60\% methanol, the helicity increases and the apoprotein goes into a helical denatured state. The conformations are also probed by the charge states produced in ESI-MS and by hydrogen/deuterium (H/D) exchange with mass measurement by ESI-MS. At 0-30\% methanol, native hMb produces relatively low charge states (9(+)-13(+)) in ESI-MS and exchanges relatively few hydrogens. In 35-40\% methanol, at which an intermediate is formed, there is a bimodal distribution of hMb ions with both low (9(+)-13(+)) and high (14(+)-23(+)) charge states and also a high charge state distribution (12(+)-26(+)) of apomyoglobin (aMb) ions. Low and high charge states of hMb and a high charge state of aMb all show the same H/D exchange rate, indicating that an unfolded hMb intermediate interconverts between folded hMb and unfolded aMb. The charge state distribution for the unfolded hMb intermediate observed here is similar to that of the recently reported transient intermediate formed during the acid denaturation of hMb. At 50\% alcohol the protein produces predominantly high charge states of aMb ions and shows H/D exchange rates close to those of the acid-denatured protein. H/D exchange of the helical denatured protein at alcohol concentrations >60\%, at which high charge states of aMb are produced, shows that the protein structure is more protected than at similar to 50\% methanol.},
	keywords = {AMIDE HYDROGEN-EXCHANGE, APOMYOGLOBIN, BETA-LACTOGLOBULIN, CYTOCHROME-C, ELECTROSPRAY-IONIZATION, FOLDING INTERMEDIATE, IONIZATION MASS-SPECTROMETRY, MOLTEN GLOBULE INTERMEDIATE, SPERM-WHALE, STRUCTURAL-CHARACTERIZATION, X-RAY-SCATTERING},
	isbn = {0006-2960},
	url = {<Go to ISI>://000165602400040},
	author = {Babu, K. R. and Douglas, D. J.}
}
