1. Research Group of Peptide Chemistry; Hungarian Academy of Sciences; P.O. Box 32, H-1518 Budapest 112 Hungary
2. Department of Genetics, Cell- and Immunobiology; Semmelweis University; Nagyvárad tér 4 Budapest 1089 Hungary
3. Department of Organic Chemistry; Eötvös Loránd University; P.O. Box 32, H-1518 Budapest 112 Hungary