Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Picture (Angew. Chem. Int. Ed. Engl. 13/14/1996)
The cover picture shows a ribbon model of a hairpin pyrrole/imidazole polyamide–oligonucleotide simultaneously binding the major and minor grooves of DNA (red circles: N-methylimidazole; blue circles: N-methylimidazole; blue circles: N-methylpyrrole rings; diamond: β-alanine). The structural formulas on the right depict the molecular interactions responsible for sequence-specific recognition: T · AT and C + GC base triplets are formed by Hoogstein hydrogen bonding of T to a Watson–Crick AT base pair and protonated MeC to a Watson–Crick GC base pair. On the left is the complex of the polyamide ImPyPy-γ-ImPyPy-β with the site 5'-TGACA-3' (circles with dots: lone pairs on N3 of purines and O2 of pyrimidines; circles containing an H: N2 hydrogen on guanine; dashed lines: putative hydrogen bonds). The energetics and specificity of the complex is reported by Szewczyk et. al. on pages 1487 ff. The picture was generated with MacDraw Pro software.