Department of Biochemistry, University of Zürich, Winterthurerstrasse 190. dhuang@bioc.uzh.ch|Department of Biochemistry, University of Zürich, Winterthurerstrasse 190. dhuang@bioc.uzh.ch|Department of Biochemistry, University of Zürich, Winterthurerstrasse 190. dhuang@bioc.uzh.ch|Department of Biochemistry, University of Zürich, Winterthurerstrasse 190. dhuang@bioc.uzh.ch|Department of Biochemistry, University of Zürich, Winterthurerstrasse 190. dhuang@bioc.uzh.ch