Tracking Flavin Conformations in Protein Crystal Structures with Raman Spectroscopy and QM/MM Calculations


  • This research was supported by the Steering Board for Molecular Life Sciences at the University of Oslo (EMBIO) and the Norwegian Research Council (grants 177661V30 and 138370V30; synchrotron-related research in the Oslo region, SYGOR). We thank the team at the Swiss–Norwegian Beamline (BM01) at the ESRF for their valuable help. We also thank Dr. Giorgio Zoppellaro for helpful discussions. QM/MM=quantum mechanical/molecular mechanical.


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Damaged goods? Detailed knowledge of the cofactor conformation is essential for the functional analysis of flavoenzyme crystal structures. However, photoelectrons generated by X-rays during crystal-data collection can reduce the flavin cofactor and thus change its geometry (see picture). Monitoring of the flavin vibrational modes by Raman spectroscopy during X-ray crystal-data collection provided important information on the actual flavin state.