Structure and stability of a dimeric g-quadruplex formed by cyclic oligonucleotides.
We have studied the structure and stability of the cyclic dodecamer d<pGGGTTAGGGTTA>, containing two copies of the human telomeric repeat. In the presence of sodium, NMR data are consistent with a dimeric structure of the molecule in which two cycles self-associate forming a quadruplex with three guanine tetrads connected by edgewise loops. The two macrocycles are arranged in a parallel way, and the dimeric structure exhibits a high melting temperature. These results indicate that cyclization of the phosphodiester chain does not prevent quadruplex formation, although it affects the global topology of the quadruplex.
Casals
Joan
J
Departament de Química Orgànica, Universitat de Barcelona, C/. Martí i Franquès 1, 08028 Barcelona, Spain.
Viladoms
Júlia
J
Pedroso
Enrique
E
González
Carlos
C