Fluorescent nucleotides and labeling methods using the same

A fluorescent nucleotide represented by the formula:

• X—Y—Z wherein,
• X represents a residue of a natural or non-natural nucleotide, an oligonucleotide, a polynucleotide, or a derivative thereof which binds to Y at a basic moiety of said residue;
• Y represents a divalent bridging group or a single bond;
• Z represents a monovalent group derived from:
• a compound represented by the following general formula (I):
• 12
• wherein, R1, R2, R3, and R4 independently represent a substituted or unsubstituted alkyl group, R3 and R4 may bind to each other to form a saturated or unsaturated ring;
• V1, V2, V3, V4, V5, and V6 represents a hydrogen atom or a substituent, V1 and V2, V2 and V3, V4 and V5, and/or V5 and V6 may bind to each other to form a saturated or unsaturated ring;
• L1, L2, L3, L4, L5, L6 and L7 independently represent a substituted or unsubstituted methine group;
• W represents an oxygen atom, a sulfur atom, —C(R3)(R4)— or —N(R5)— wherein R3, R4, and R5 independently represent a substituted or unsubstituted alkyl group;
• Q represents a nitrogen atom or —C(V7)— wherein V7 represents a hydrogen atom or a monovalent substituent and may bind to V6 to form a saturated or unsaturated ring;
• M represents a counter ion;
• m represents a number required to neutralize the charge of the molecule;
• s represents 0 or 1;
• t represents 0 or 1;
• and u represents 0 or 1;
• a compound represented by the following general formula (II):
• 13
• wherein, V1, V2, V3, R1, R2, R3, R4, L1, L2, L3, L4, L5, L6, L7, W, M, m, s, t, and u have the same meanings as defined above;
• V8 represents a hydrogen atom or a monovalent substituent, provided that, when W represents —N(R5)— or —C(R3)(R4)—, V8 may bind to a substituent on W to form a saturated or unsaturated ring;
• or
• a compound represented by the following general formula (III):
• 14
• wherein, V1, V2, V3, R1, R2, R3, R4, L1, L2, L3, L4, L5, L6, L7, W, M, m, s, t, and u have the same meanings as defined above;
• E represents a nitrogen atom or —C(R6)═(R6 represents a hydrogen atom or a monovalent substituent;
• V9 represents a hydrogen atom or a monovalent substituent and V9 may bind to R6 to form a saturated or unsaturated ring,
• and Z binds to Y at a reactive group existing in R1 or R2.