02457nas a2200229   4500008004100000022001400041245010100055210006900156260008000225300001600305490000800321520158800329653003001917653002001947653002301967653002901990100001502019700002302034700002202057700001902079856012902098       2014                        eng d  a0027-842400aModeling gating charge and voltage changes in response to charge separation in membrane proteins0 aModeling gating charge and voltage changes in response to charge  a2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USAbNATL ACAD SCIENCEScAUG  a11353-113580 v1113 a<p>Measurements of voltage changes in response to charge separation within membrane proteins can offer fundamental information on mechanisms of charge transport and displacement processes. A recent example is provided by studies of cytochrome c oxidase. However, the interpretation of the observed voltage changes in terms of the number of charge equivalents and transfer distances is far from being trivial or unique. Using continuum approaches to describe the voltage generation may involve significant uncertainties and reliable microscopic simulations are not yet available. Here, we attempt to solve this problem by using a coarse-grained model of membrane proteins, which includes an explicit description of the membrane, the electrolytes, and the electrodes. The model evaluates the gating charges and the electrode potentials (c.f. measured voltage) upon charge transfer within the protein. The accuracy of the model is evaluated by a comparison of measured voltage changes associated with electron and proton transfer in bacterial photosynthetic reaction centers to those calculated using our coarse-grained model. The calculations reproduce the experimental observations and thus indicate that the method is of general use. Interestingly, it is found that charge-separation processes with different spatial directions (but the same distance perpendicular to the membrane) can give similar observed voltage changes, which indicates that caution should be exercised when using simplified interpretation of the relationship between charge displacement and voltage changes.</p>10abacterial reaction center10aelectrogenicity10amembrane potential10aproton/electron transfer1 aKim, Ilsoo1 aChakrabarty, Suman1 aBrzezinski, Peter1 aWarshel, Arieh  uhttps://library.ncl.res.in/content/modeling-gating-charge-and-voltage-changes-response-charge-separation-membrane-proteins-0