1. Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ulitsa Miklukho‐Maklaya 16/10, 117997 Moscow V-437, Russian Federation.
2. Lomonosov Moscow State University, Moscow 119991, Russian Federation.
3. European Molecular Biology Laboratory, Hamburg Unit, c/o German Synchrotron Research Center, Notkestrasse 85, 22603 Hamburg, Germany.
4. Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road MB-10, La Jolla, CA 92037, USA.
5. Krebs Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, U.K.