Institute of Biophysics and Physical Biochemistry, University of Regensburg, 93040 Regensburg, Germany. Rainer.Merkl@biologie.uni-regensburg.de|Institute of Biophysics and Physical Biochemistry, University of Regensburg, 93040 Regensburg, Germany. Rainer.Merkl@biologie.uni-regensburg.de|Institute of Biophysics and Physical Biochemistry, University of Regensburg, 93040 Regensburg, Germany. Rainer.Merkl@biologie.uni-regensburg.de|Institute of Biophysics and Physical Biochemistry, University of Regensburg, 93040 Regensburg, Germany. Rainer.Merkl@biologie.uni-regensburg.de|Institute of Biophysics and Physical Biochemistry, University of Regensburg, 93040 Regensburg, Germany. Rainer.Merkl@biologie.uni-regensburg.de