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@ARTICLE{Seemann:111840,
      author       = {Seemann, Klaus M. and Kiefersauer, Reiner and Jacob, Uwe
                      and Kuhn, Bernd},
      title        = {{O}ptical p{H} {D}etection within a {P}rotein {C}rystal},
      journal      = {The journal of physical chemistry $\<Washington,$ $DC\>$ /
                      B},
      volume       = {116},
      issn         = {1520-6106},
      address      = {Washington, DC},
      publisher    = {Soc.},
      reportid     = {PreJuSER-111840},
      pages        = {9873-9881},
      year         = {2012},
      note         = {Record converted from VDB: 16.11.2012},
      abstract     = {The pH is one of the key parameters governing protein
                      conformation and activity. In protein crystals, however, the
                      pH is so far not accessible by experiment. Here, we report
                      on the optical detection of the pH in a lysozyme crystal
                      employing the pH-sensitive fluorescent dyes SNARF-1 and
                      SNARF-4F. The molecular probes were loaded into the crystal
                      by diffusion. Two-dimensional fluorescence spectra of the
                      labeled protein crystal were recorded, and the average pH of
                      the crystal at different bath pH's was determined by
                      calibrating fluorescence peak ratios. In addition, we used
                      two-photon microscopy to spatially resolve the pH inside a
                      lysozyme crystal three-dimensionally and to follow pH
                      changes in response to a pH change of the bath over time. At
                      equilibrium at bath pH between 5.5 and 8.0, we found a pH in
                      the water-filled crystal channels that was ΔpH = -0.3 to
                      -1.0 lower than that of the bath. This corresponds to a 2-
                      to 10-fold higher proton concentration in the crystal
                      channels than in the bath. The lower pH at equilibrium in
                      the crystal channels can be explained by slower proton
                      diffusion in the channels than in the bath and a resulting
                      proton accumulation in the crystal for conservation of mass
                      and so an equilibrium of proton flux.},
      keywords     = {J (WoSType)},
      cin          = {PGI-6},
      ddc          = {530},
      cid          = {I:(DE-Juel1)PGI-6-20110106},
      pnm          = {Grundlagen für zukünftige Informationstechnologien},
      pid          = {G:(DE-Juel1)FUEK412},
      shelfmark    = {Chemistry, Physical},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:22834887},
      UT           = {WOS:000307749100001},
      doi          = {10.1021/jp2103512},
      url          = {https://juser.fz-juelich.de/record/111840},
}