Detection of guanine–adenine mismatches by surface plasmon resonance sensor carrying naphthyridine–azaquinolone hybrid on the surface

摘要

We have discovered a new molecule naphthyridine–azaquinolone hybrid (Npt–Azq) that strongly stabilized the guanine-adenine (G-A) mismatch in duplex DNA. In the presence of Npt–Azq, the melting temperature (Tm) of 5'-d(CTA ACG GAA TG)-3'/3'-d(GAT TGA CTT AC)-5' containing a single G-A mismatch increased by 15.4 ℃, whereas fully matched duplex increased its Tm only by 2.2 ℃. Npt–Azq was immobilized on the sensor surface for the surface plasmon resonance (SPR) assay to examine SPR detection of duplexes containing a G-A mismatch. Distinct SPR signals were observed when 27mer DNA containing a G-A mismatch was analyzed by the Npt–Azq immobilized sensor surfaces, whereas the signal of the fully matched duplex was 6-fold weaker in intensity. The SPR signals for the G-A mismatch were proportional to the concentration of DNA in a range up to 1 μM, confirming that the SPR signal is in fact due to the binding of the G-A mismatch to Npt–Azq immobilized on the surface. Examination of all 16 G-A mismatches regarding the flanking sequence revealed that the sensor surface reported here is applicable to eight flanking sequences, covering 50% of all possible G-A mismatches.