Abstract: To provide a novel and useful technique capable of achieving an improve S/N ratio in a hybridization detection technique using an intercalator. A method is provided wherein a hybridization is detected by measuring a fluorescence intensity from an intercalator I binding to a probe nucleic acid P and a complementary strand site of a target nucleic acid T. In the invention, a single-stranded target nucleic acid Ts, a single-stranded probe nucleic acid Ps forming no complementary strand and surplus nucleic acid moieties T11, T12 of a target nucleic acid T, which induce generation of noise fluorescence owing to the nonspecific binding of the intercalator I thereto, are digested and degraded with an enzyme having nuclease activity, such as a nucleolytic enzyme (nuclease) or the like.

Abstract: Disclosed herein is an SNP discrimination assay for discriminating base species of an SNP in a specific gene in a sample, which includes the steps of hybridizing four detection probes, which have at least a flanking sequence around an SNP in the gene and are different in base species at a site of the SNP, with a target nucleic acid in the sample, the target nucleic acid having at least the flanking sequence around the SN in the gene, respectively, cleaving three of four double-stranded nucleic acids, which contain noncomplementary base pairs, respectively, at sites of the noncomplementary base pairs, denaturing only the three double-stranded nucleic acids, which have been cleaved at the sites of the noncomplementary base pairs, into single-stranded forms, and detecting one of the four detection probes, the one detection probe still retaining a double-stranded form after the nucleic acid denaturation step.

Abstract: Disclosed is a method for the detection of an interaction between substances. According to the method, a salt-containing HEPES buffer is allowed to exist in a reaction region that provides a place of interaction for the interaction. The concentration of the salt in the salt-containing HEPES buffer may be adjusted such that one or more substances each having a negative charge, such as a probe nucleic acid, target nucleic acid and/or intercalator, can be prevented from undergoing non-specific adsorption on a positively-charged surface of a solid phase. Also disclosed are an interaction detecting unit including the reaction region and a medium existing in the reaction region and including the salt-containing HEPES buffer; a bioassay plate including a DNA chip provided with a number of such interaction detecting units; a system for detecting an interaction such as hybridization; and a reagent kit including the salt-containing HEPES buffer.