Qiang Gao

Publications (2)5.93 Total impact

• Article: DNA-binding small-ligand-immobilized surface plasmon resonance biosensor for detecting thymine-related single-nucleotide polymorphisms.

  Sara Miura, Seiichi Nishizawa, Akinori Suzuki, Yukiko Fujimoto, Katsuya Ono, Qiang Gao, Norio Teramae
  [show abstract] [hide abstract]
  ABSTRACT: A surface plasmon resonance (SPR) biosensor that carries DNA-binding small ligands has been developed for the detection of single-nucleotide polymorphisms (SNPs). 3,5-Diaminopyrazine derivatives, with a hydrogen-bonding profile fully complementary to the thymine base, were utilized as recognition elements on the sensor surface, and a target single-stranded DNA sequence was hybridized with a DNA probe containing an abasic site to place this site opposite a nucleobase to be detected. In a continuous flow of sample solutions buffered to pH 6.4 (0.25 M NaCl), the 3,5-diaminopyrazine-based SPR sensor can detect an orphan nucleobase in the duplex with a clear selectivity for thymine over cytosine, guanine, and adenine (5'-GTT GGA GCT GXG GGC GTA GGC-3'/3'-CAA CCT CGA CNC CCG CAT CCG-5'; X=abasic site, N=target nucleobase G, C, A, or T). The SPR response was linear in the concentration range 10-100 nM. Allele discrimination is possible based on the combination of different binding surfaces in a flow cell of the SPR system, which is demonstrated for the analysis of the thymine/cytosine mutation present in 63-meric polymerase chain reaction (PCR) amplification products (Ha-ras gene, codon 12, antisense strand). Comparison with a bulk assay based on 3,5-diaminopyrazine/DNA binding shows that the immobilization of 3,5-diaminopyrazine derivatives on the SPR sensor allows more sensitive detection of the target DNA sequence, and binding selectivity can be tuned by controlling the salt concentration of sample solutions. These features of the DNA-binding small-molecule-immobilized SPR sensor are discussed as a basis for the design of SPR biosensors for SNP genotyping.
  Chemistry 11/2011; 17(50):14104-10. · 5.93 Impact Factor
• Article: Strong binding of naphthyridine derivatives to a guanine base in DNA duplexes containing an AP site.

  Qiang Gao, Hiroyuki Satake, Qing Dai, Katsuya Ono, Seiichi Nishizawa, Norio Teramae
  [show abstract] [hide abstract]
  ABSTRACT: By using UV thermal denaturation and isothermal titration calorimetry (ITC), we examine the binding behaviors of a hydrogen bond-forming ligand, 2-acetylamino-7-methyl-1,8-naphthyridine (AcMND), with a guanine base opposite an abasic site (AP site) in a DNA duplex (5'-TCC AGX GCA AC-3'/3'-AGG TCG CGT TG-5', X = AP site, G = target). In the presence of AcMND, the melting temperature (Tm) of the AP site-containing DNA duplex increases by 8.6 degrees C while hardly any change in Tm is observed for a corresponding normal duplex that has no AP sites. The examination by ITC reveals that, in solutions buffered to pH 7.0 (at 10 degrees C, I = 0.11 M), AcMND is able to recognize guanine base with a 1:1 binding constant of 3.4x10(5) M(-1). The ligand-nucleotide interaction is clearly enthalpy driven, with deltaH(o) of -12.5 kcal/mol. We discuss these binding functions of AcMND at the AP site with a view towards development of ligand-based assay for SNPs (single-nucleotide polymorphisms) typing.
  Nucleic Acids Symposium Series 02/2005;