1. Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, University of Stockholm, S-106 91 Stockholm,1
2. A. N. Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky Prospect 33, 117071, Moscow, Russia,2 and
3. Center for Structural Biochemistry, Novum, S-141 57 Huddinge,3 and
4. Department of Engineering and Natural Sciences, University of Växjö, S-351 95 Växjö,4 Sweden