1. The Julius Spokojny Bioorganic Chemistry Laboratory; Department of Chemistry; Bar-Ilan University; Ramat-Gan 5290002 Israel
2. C.A.I.R. Institute, The Safdiè AIDS and Immunology Research Center; The Mina & Everard Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat-Gan 5290002 Israel
3. Department of Biological Regulation; The Weizmann Institute of Science; Rehovot 7610001 Israel