Mismatch-recognizing molecules

A compound represented by the general formula (II):

• (wherein R and R1 are a hydrogen atom, an alkyl group having 1 to 15 carbon atoms wherein one or more carbon atoms in said alkyl group are optionally substituted by oxygen atom or nitrogen atom, an alkoxy group having 1 to 15 carbon atoms wherein one or more carbon atoms in said alkoxy group are optionally substituted by oxygen atom or nitrogen atom, or a mono- or dialkylamino group having 1 to 15 carbon atoms wherein one or more carbon atoms in said alkylamino group are optionally substituted by oxygen atom or nitrogen atom, R2 is an alkyl group having 1 to 20 carbon atoms wherein one or more carbon atoms in said alkyl group are optionally substituted by oxygen atom, nitrogen atom or carbonyl group), or an immobilized form thereof.

A method for detecting an abnormal base sequence in DNA or RNA comprising hybridizing a single-stranded DNA or RNA of a specimen and the corresponding DNA or RNA thereto having a normal base sequence, subsequently constructing a pseudo-base-pairing with a base pair, which can not construct a normal base pairing, in said hybridized DNA or RNA by using a compound represented by the general formula (I):

• A—L≦B (I)
• (wherein A is a chemical structural moiety constructing a complementary base pairing with a base of a base pair which can not construct a normal base pairing, B is a chemical structural moiety constructing another complementary base pairing with the other base of the base pair which can not construct a normal base pairing, and L is a linker structure linking the chemical structural moieties A and B), having a chemical structural moiety A and a chemical structural moiety B, both of which can construct base pairings with corresponding bases of the base pair, respectively, and a linker structure L linking said chemical structural moieties A and B, assaying the construction of said pseudo-base-pairing.