Synthesis and characterization of a bunchy oligonucleotide forming a monomolecular parallel quadruplex structure in solution

A cluster of four d(TG4T) hexanucleotides with the 3′-ends linked together by a bunchy spacer has been synthesized and shown to form a monomolecular parallel quadruplex 5 in solution characterized by four G-quartets. 1H NMR spectroscopy and CD thermal denaturation experiments indicate the monomolecular quadruplex (5) to be more stable than the tetramolecular counterpart [d(TG4T)]4.