@article {5225,
	title = {Reaction of human myoglobin and nitric oxide - Heme iron or protein sulfhydryl (S) nitrosation dependence on the absence or presence of oxygen},
	journal = {Journal of Biological Chemistry},
	volume = {276},
	number = {6},
	year = {2001},
	note = {ISI Document Delivery No.: 401HBTimes Cited: 33Cited Reference Count: 58},
	month = {Feb},
	pages = {3991-3998},
	type = {Article},
	abstract = {The amino acid sequence of human myoglobin (Mb) is similar to other mammalian Mb except for a unique cysteine residue at position 110 (Cys(110)). Anaerobic treatment of ferrous forms of wild-type human Rib, the C110A variant of human Mb or horse heart Mb, with either authentic NO or chemically derived NO in vitro yields heme-NO complexes as detected by electron paramagnetic resonance spectroscopy (EPR). By contrast, no EPR-detectable heme-NO complex was observed from the aerobic reactions of NO and either the ferric or oxy-Mb forms of wild-type human or horse heart myoglobins, Mass analyses of wild-type human Mb treated aerobically with NO indicated a mass increase of similar to 30 atomic mass units (i.e,, NO/Mb = 1 mol/mol), Mass analyses of the corresponding apoprotein after heme removal showed that NO was associated with the apoprotein fraction. New electronic maxima were detected at A(333) nm (epsilon = 3665 +/- 90 mol(-1) cm(-1); mean +/- S.D.) and A(545) nm (epsilon = 44 +/- 3 mol(-1) cm(-1)) in solutions of S-nitrosated wild-type human Mb (similar to S-nitrosoglutathione), Importantly, the sulfhydryl S-H stretch vibration for Cys(110) measured by Fourier transform infrared (nu similar to 2552 cm(-1)) was absent for both holo- and apo- forms of the wild-type human protein after aerobic treatment of the protein with NO. Together, these data indicate that the reaction of wild-type human Mb and NO yields either heme-NO or a novel S-nitrosated protein dependent on the oxidation state of the heme iron and the presence or absence of dioxygen.},
	keywords = {ELECTRON-SPIN-RESONANCE, GLUTATHIONE, HEMOGLOBIN, HUMAN SKELETAL-MUSCLE, METMYOGLOBIN, NITROSOTHIOLS, OXIDATION, RELAXING FACTOR, SMOOTH-MUSCLE, VASCULAR TONE},
	isbn = {0021-9258},
	url = {<Go to ISI>://000166921200038},
	author = {Witting, P. K. and Douglas, D. J. and Mauk, A. G.}
}
@article {4978,
	title = {Reaction of human myoglobin and H2O2 - Involvement of a thiyl radical produced at cysteine 110},
	journal = {Journal of Biological Chemistry},
	volume = {275},
	number = {27},
	year = {2000},
	note = {ISI Document Delivery No.: 332QGTimes Cited: 55Cited Reference Count: 52},
	month = {Jul},
	pages = {20391-20398},
	type = {Article},
	abstract = {The human myoglobin (Mb) sequence is similar to other mammalian Mb sequences, except for a unique cysteine at position 110. Reaction of wild-type recombinant human Mb, the C110A variant of human Mb, or horse heart Mb with H2O2 (protein/H2O2 = 1:1.2 mol/mol) resulted in formation of tryptophan peroxyl (Trp-OO.) and tyrosine phenoxyl radicals as detected by EPR spectroscopy at 77 K. For wild-type human Mb, a second radical (g similar to 2.036) was detected after decay of Trp-OO. that was not observed for the C110A variant or horse heart Mb. When the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) was included in the reaction mixture at protein/DMPO ratios less than or equal to 1:10 mol/mol, a DMPO adduct exhibiting broad absorptions was detected. Hyperfine couplings of this radical indicated a DMPO-thiyl radical. Incubation of mild-type human Mb with thiol-blocking reagents prior to reaction with peroxide inhibited DMPO adduct formation, whereas at protein/DMPO ratios greater than or equal to 1:25 mol/mol, DMPO-tyrosyl radical adducts were detected. Mass spectrometry of wild-type human Mb following reaction with H2O2 demonstrated the formation of a homodimer (mass of 34,107 +/- 5 atomic mass units) sensitive to reducing conditions. The human Mb C110A variant afforded no dimer under identical conditions. Together, these data indicate that reaction of wild-type human Mb and H2O2 differs from the corresponding reaction of other myoglobin species by formation of thiyl radicals that lead to a homodimer through intermolecular disulfide bond formation.},
	keywords = {ASCORBATE, CROSS-LINKING, enzyme catalysis, HEMOGLOBIN, HYDROGEN-PEROXIDE, LOW-DENSITY-LIPOPROTEIN, METMYOGLOBIN, OXIDATION, SPERM WHALE MYOGLOBIN, SPIN ADDUCTS},
	isbn = {0021-9258},
	url = {<Go to ISI>://000088084500025},
	author = {Witting, P. K. and Douglas, D. J. and Mauk, A. G.}
}
@article {4227,
	title = {Stability of a highly charged noncovalent complex in the gas phase: Holomyoglobin},
	journal = {Rapid Communications in Mass Spectrometry},
	volume = {12},
	number = {15},
	year = {1998},
	note = {ISI Document Delivery No.: 105GATimes Cited: 33Cited Reference Count: 56},
	pages = {1003-1010},
	type = {Article},
	abstract = {Gas phase holomyoglobin (hMb) ions in charge states +7 to +21 were formed by electrospray ionization in combination with a continuous-flow mixing apparatus. Collision cross section measurements show that the highly charged ions are somewhat unfolded in comparison to low charge states but still retain a considerable degree of folding. A new collision model is presented which calculates the relative energies transferred to complexes in tandem mass spectrometry. Tandem mass spectrometry and ion trapping experiments both show that the energies required to dissociate heme from the highly charged heme-protein complexes in the gas phase are similar to those of low charge states, previously shown in literature ion cyclotron resonance experiments to be 0.7-1.0 eV, These energies are comparable to those of the heme binding energy in solution. The results suggest that even for the highly charged hMb ions which have unfolded somewhat, the heme-protein interactions remain relatively unperturbed. (C) 1998 John Wiley \& Sons, Ltd.},
	keywords = {CONFORMATION, CYTOCHROME-C, ELECTROSPRAY-IONIZATION, ion-molecule, IONIZATION MASS-SPECTROMETRY, METMYOGLOBIN, MYOGLOBIN, PROTEIN IONS, PROTON-TRANSFER REACTIVITY, QUADRUPOLE, reaction},
	isbn = {0951-4198},
	url = {<Go to ISI>://000075063300003},
	author = {Chen, Y. L. and Campbell, J. M. and Collings, B. A. and Konermann, L. and Douglas, D. J.}
}
@article {4030,
	title = {Acid-induced denaturation of myoglobin studied by time-resolved electrospray ionization mass spectrometry},
	journal = {Biochemistry},
	volume = {36},
	number = {21},
	year = {1997},
	note = {ISI Document Delivery No.: XB321Times Cited: 74Cited Reference Count: 43},
	month = {May},
	pages = {6448-6454},
	type = {Article},
	abstract = {The acid-induced denaturation of holo-myoglobin (hMb) following a pH-jump from 6.5 to 3.2 has been studied by electrospray ionization (ESI) mass spectrometry in combination with a continuous flow mixing technique (time-resolved ESI MS). Different protein conformations are detected by the different charge state distributions that they generate during ESI. The changes in intensity of the peaks in the mass spectrum as a function of time can be described by two exponential lifetimes of 0.38 +/- 0.06 s and 6.1 +/- 0.5 s, respectively. The acid-induced denaturation of hMb was also studied in stopped-flow experiments by monitoring changes in the Soret absorption. The lifetimes measured by this method are in good agreement with those obtained by time-resolved ESI MS. The shorter lifetime is associated with the formation of a transient intermediate which shows the mass of the intact heme-protein complex but leads to the formation of much higher charge states during ESI than native hMb at pH 6.5. This form of hMb has an absorption spectrum similar to that of the native protein, indicating a relatively unperturbed chromophore environment inside the heme binding pocket. The intermediate can thus be characterized as an unfolded form of hMb with essentially intact heme-protein interactions. The longer of the two lifetimes is associated with the formation of a product which has a blue-shifted absorption spectrum with a much lower maximum absorption coefficient than observed for native hMb. In the ESI mass spectrum, this product appears as the apoprotein with high charge states which indicates the disruption of the native heme-protein interactions and a considerable degree of unfolding compared to native apo-myoglobin. The mechanism of acid-induced denaturation of hMb, therefore, appears to follow the sequence (heme protein)(native) {\textendash}> (heme-protein)(unfolded) {\textendash}> heme + (protein)(unfolded).},
	keywords = {APOMYOGLOBIN, HEME-PROTEINS, INTERMEDIATE, IONS, LOW PH, METMYOGLOBIN, PROBING CONFORMATIONAL-CHANGES, RESOLUTION, SPERM WHALE, STABILITY},
	isbn = {0006-2960},
	url = {<Go to ISI>://A1997XB32100022},
	author = {Konermann, L. and Rosell, F. I. and Mauk, A. G. and Douglas, D. J.}
}
