Fig. 3. Binary anion–π interactions in biological systems. (a) Post-reactive state of endonuclease BamHI complexed to DNA (PDB code ; 3BAM), where Asp–π interactions are shown. (b) C-terminal domain of human protein U1A bound to RNA (PDB code ; 1URN), where the Asp92–π interaction is shown. (c) Active site of the complex of pyridoxal-5′-phosphate-dependent catalytic antibody ; 15A9 with a phosphopyridoxyl-l-alanine (PPL-A) substrate analogue (PDB code ; 1WC7), where the Glu58–π interaction is shown.
