[Legacy Report] Vibrational Properties of Quinones in Photosynthetic Reaction Centers

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Calculated and experimental spectra for neutral ubiquinone in solution
are very different from the spectra associated with ubiquinone in the
QA binding in purple bacterial reaction centers. For this reason an
ONIOM method was undertaken in which the pigment was treated using
density functional theory based methods while the protein was treated
using molecular mechanics. The ONIOM calculations not only modeled the
experimental QA FTIR difference spectra but also resolved the long
standing issue of whether a very strong hydrogen bond exists between
the bound ubiquinone and the imidazole nitrogen of a histidine residue
(HisM219).

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