Triplex DNA is due to
Triple-stranded DNA is a DNA structure in which three oligonucleotides wind around each other and form a triple helix. In this structure, one strand binds to a B-form DNA double helix through Hoogsteen or reversed Hoogsteen hydrogen bonds. For example, a nucleobase T binds to a Watson-Crick base-pairing of T-A by Hoogsteen hydrogen bonds between an AxT pair (x represents a Hoogsteen base pair). An N-3 protonated cytosine, represented as C+, can also form a base-triplet with a C-G pair through the Hoogsteen base-pairing of an GxC+. Thus, the triple-helical DNAs using these Hoogsteen pairings consist of two homopyrimidines and one homopurine, and the homopyrimidine third strand is parallel to the homopurine strand.
Hoogsteen pairing
Palindromic sequences
Large no. of guanosine repeats
Polypyramidine tracts
Metabolism of nucleic acids