1. The Institute of ChemistryThe Hebrew University of Jerusalem Edmond J. Safra Givat Ram, Jerusalem 91904 Israel
2. Department of BiochemistryCase Western Reserve University Cleveland Ohio 44106 USA
3. Wolfson Center for Applied Structural BiologyThe Hebrew University of Jerusalem Edmond J. Safra Givat Ram, Jerusalem 91904 Israel
4. Department of Biochemistry & Molecular BiologyIndiana University School of Medicine Indianapolis IN 46202 USA