Recognition of Anionic Porphyrins by DNA Aptamers †

DNA sequences were isolated by in vitro selection for binding to N-methylmesoporphyrin IX (NMM), a molecule that behaves as a stable transition-state analogue for porphyrin chelatases. Clones approximately 280 and approximately 120 nucleotides long were obtained, which bound to NMM with sub-micromolar affinity but bound mesoporphyrin IX (MPIX), as well as various metalloderivatives of MPIX, with lower affinity. Footprinting experiments with …