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| Recognition of anionic porphyrins by DNA aptamers |
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| Author(s): Li YF, Geyer CR, Sen D |
| Source: BIOCHEMISTRY Volume: 35 Issue: 21 Pages: 6911-6922 Published: MAY 28 1996 |
| Times Cited: 80 References: 52 |
| Abstract: 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 similar to 280 and similar to 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 dimethyl sulfate, DNase I, and bound hemin molecules activated by superoxide identified a series of short guanine-rich motifs to be the binding sites for the various porphyrins. One clone, PS2, examined in depth, gave a methylation footprint with bound NMM but not with bound MPIX nor with a number of metalloporphyrins. The binding domain of PS2, synthesized as a short oligonucleotide, itself showed high-affinity binding to NMM. The binding sequences from different clones were loosely homologous, and the footprinting data were consistent with their folding to form one or more guanine quarters in the presence of NMM. Ultraviolet-visible absorption and circular dichroism spectroscopy of the DNA-NMM complexes indicates, however, that the interaction is not primarily intercalative in nature. The preferential binding of NMM by these aptamers raises the possibility of their being able to catalyze the chelation;of metal ions by the porphyrin MPIX. |
| Document Type: Article |
| Language: English |
Addresses:
1. SIMON FRASER UNIV, INST MOLEC BIOL & BIOTCHEM, BURNABY, BC V5A 1S6 CANADA |
| Publisher: AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 |
| Subject Category: Biochemistry & Molecular Biology |
| IDS Number: UN288 |
| ISSN: 0006-2960 |
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