Recognition of single-nucleotide polymorphism (SNP) was proposed in this work on the basis of fluorescence enhancement of an inorganic ligand, terbium ion (Tb^3＋), upon binding at an abasic (AP) site in DNA. The AP site was deliberately introduced in a probe strand just opposite the base of interest in a target strand. Selective binding of Tb^3＋ at the AP site was found by observations of its characteristic fluorescence enhancement for AP site-containing DNA by comparison with fully matched DNA without the AP site. The enhancement is very dependent on the target base and the bases flanking the AP site. When the target base is G, the maximum enhancement of Tb^3＋ fluorescence can be obtained especially for guanines flanking the AP site. This method was successfully applied in detection of P177R mutation of codon 177 in cancer repression gene p53, manifesting its potential applications in SNP detection with signal-on fashion.

Key words: abasic stie, single-nucleotide polymorphism, terbium ion, fluorescence enhancement, molecular recognition