Gmelin, W. [P:(DE-HGF)0] ; Zeth, K. [P:(DE-HGF)0] ; Efremov, R. [P:(DE-Juel1)VDB4616] ; Heberle, J. [P:(DE-Juel1)VDB572] ; Tittor, J. [P:(DE-HGF)0] ; Oesterhelt, D. [P:(DE-HGF)0]