@article {1483, title = {Coulomb effects in binding of heme in gas-phase ions of myoglobin}, journal = {Rapid Communications in Mass Spectrometry}, volume = {20}, number = {2}, year = {2006}, note = {ISI Document Delivery No.: 003PGTimes Cited: 3Cited Reference Count: 31}, pages = {111-117}, type = {Article}, abstract = {Coulomb effects in binding of heme in gas-phase holomyoglobin ions are studied. Positive and negative ions are formed from solution myoglobin with Fe2+ (ferromyoglobin) and Fe3+ (ferrimyoglobin). The energy that must be added to the resulting holomyoglobin ions to cause heme loss has been measured by triple-quadrupole tandem mass spectrometry. With negative ions, neutral heme is lost regardless of the charge state of Fe in solution. It is likely that the Fe3+ is reduced to Fe2+ in the negative electrospray process. With positive ions, predominantly neutral heme loss is observed with ions formed from ferromyoglobin in solution, and positive heme loss with ions formed from ferrimyoglobin in solution. The energies required to induce neutral heme loss are similar for positive and negative ions. The energies required to induce charged heme loss from positive holomyoglobin ions are significantly less. Coulomb repulsion between the charged heme and charged protein appears to lower the barrier for heme loss. These results are consistent with a simple model potential with a long-range Coulomb repulsion and short-range attraction between the heme and protein. Copyright (c) 2005 John Wiley \& Sons, Ltd.}, keywords = {B(5), COLLISION CROSS-SECTIONS, CYTOCHROME, DISSOCIATION, ELECTROSTATIC INTERACTIONS, GLOBIN COMPLEXES, HOLOMYOGLOBIN, IONIZATION-MASS-SPECTROMETRY, PROTEINS, STABILITY, ZN-MYOGLOBIN}, isbn = {0951-4198}, url = {://000234693500006}, author = {Mark, K. J. and Douglas, D. J.} }