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@INPROCEEDINGS{Heigl:827764,
      author       = {Heigl, Raimund and Stellbrink, Jörg and Radulescu, Aurel
                      and Schweins, Ralf and Schrader, Tobias Erich and Richter,
                      Dieter},
      title        = {{C}hange of {F}ractal {D}imension during the early stages
                      of{L}ysozyme {C}rystallization},
      reportid     = {FZJ-2017-01870},
      year         = {2016},
      abstract     = {Neutron protein crystallography is a powerful tool to
                      investigate enzyme mechanisms in depth. It has the advantage
                      of providing also the hydrogen atom positions which are
                      practically invisible in x-ray crystallography. Furthermore,
                      it does not lead to a reduction of the active center due to
                      radiation damage often encountered using x-rays. Its main
                      disadvantage is the need for rather large crystals (> 0.5
                      mm3). This proves to be the biggest bottle-neck when
                      considering a neutron protein crystallography experiment. To
                      address this we concentrated on the early stages of the
                      crystallization process where the directions are set whether
                      many small crystals grow or few large ones. We used lysozyme
                      as a model system since it has been studied well in the past
                      and the phase diagram of its crystal growth is known. We
                      used a combination of three scattering techniques since the
                      involved size ranges require a large q-range. Small angle
                      neutron scattering was used in combination with static light
                      scattering on the same sample in order to obtain structural
                      information on the growing crystal seeds. In situ dynamic
                      light scattering at the neutron scattering sample cell was
                      used to obtain an overview of all sizes present in the
                      crystallization process by measuring their hydrodynamic
                      radii. The small angle neutron scattering technique requires
                      the crystallization in heavy water instead of normal water.
                      We found that the crystallization conditions did not differ
                      too much from the ones mentioned in the literature for light
                      water when using a corrected pD value of pD=pH+0.4. The
                      crystallization is initiated by mixing a 60 mg/ml Lysozyme
                      solution with a 6 $wt\%$ NaCl acetate buffer solution (both
                      at pD=4.75 and at 298 K) in a 1:1 ratio. Immediately after
                      mixing, dimers of lysozyme molecules are formed and the
                      structure factor seen in the lysozyme stock solution
                      disappears. Under the chosen conditions we could observe a
                      fractal growth of the crystal seeds with a change of the
                      fractal dimension from 1.0 to 1.7 in the first 90 min. This
                      can be interpreted as a crystal seed being formed first
                      which grows more in a linear manner with little branching.
                      Later, the space in between the branched arms is filled to
                      cross over to a more densely packed fractal. With these
                      results theoretical models of crystal growth can be
                      improved. Furthermore, the early detection of crystal seeds
                      can be used to rapidly change the crystallization conditions
                      (e. g. temperature) in order to avoid the production of more
                      crystal seeds.},
      month         = {Sep},
      date          = {2016-09-20},
      organization  = {German Conference on Neutron
                       Scattering 2016, Kiel (Germany), 20 Sep
                       2016 - 22 Sep 2016},
      subtyp        = {Outreach},
      cin          = {JCNS (München) ; Jülich Centre for Neutron Science JCNS
                      (München) ; JCNS-FRM-II / Neutronenstreuung ; JCNS-1 /
                      JCNS-2},
      cid          = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
                      I:(DE-Juel1)JCNS-1-20110106 / I:(DE-Juel1)JCNS-2-20110106},
      pnm          = {6G15 - FRM II / MLZ (POF3-6G15) / 6215 - Soft Matter,
                      Health and Life Sciences (POF3-621) / 6G4 - Jülich Centre
                      for Neutron Research (JCNS) (POF3-623) / NMI3-II - Neutron
                      Scattering and Muon Spectroscopy Integrated Initiative
                      (283883)},
      pid          = {G:(DE-HGF)POF3-6G15 / G:(DE-HGF)POF3-6215 /
                      G:(DE-HGF)POF3-6G4 / G:(EU-Grant)283883},
      experiment   = {EXP:(DE-MLZ)KWS2-20140101},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/827764},
}