1. Department of Organic and Nuclear Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague 2, Czech Republic
2. Institute of Organic Chemistry and Biochemistry AS CR, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
3. Center for Chemical Genetics, Institute of Molecular Genetics AS CR, Vídeňská 1083, 142 20 Prague 4, Czech Republic