to fold or to dimerize a dilema for modified TBA

What is it about?

Several years ago it was found a specific DNA sequence known as TBA that is made of 15 nucleotides was able to bind thrombin and become anticoagulant. The structure of this compounds has been described as a folded G-quaduplex in antiparallel orientation. In this paper we show small changes in the sequence that induces a large change in the structure and the modified TBA becomes a dimer G-quadruplex in parallel orientation. Characterization of the new structure was done by CD, UV and MS.

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Why is it important?

Quadruplex forming sequences are abundant in the genome. Specially relevant sequecnes capable of forming G-quaplex are found especially in promoter regions of oncogenes and at the end of chormosomes. The conformational diversity of the G-quadruplex structures are an important matter of study as G-quadruplex structures may vary depending of several factors such as ions, crowding agents or dehydrating conditions, pH etc... This work also indicates that mutations in this areas may induce changes.