Effect of Base Sequence on G-Wire Formation in Solution

The formation and dimensions of G-wires by different short G-rich DNA sequences in solution were investigated by dynamiclight scattering (DLS) and polyacrilamide gel electrophoresis (PAGE). To explore the basic principles of wire formation, westudied the effects of base sequence, method of preparation, temperature, and oligonucleotide concentration. Both DLS andPAGE show that thermal annealing induces much less macromolecular self-assembly than dialysis. The degree of assembly andconsequently length of G-wires (5-6 nm) are well resolved by both methods for DNA sequences with intermediate length, whilesome discrepancies appear for the shortest and longest sequences. As expected, the longest DNA sequence gives the longestmacromolecular aggregates with a length of about 11 nm as estimated by DLS. The quadruplex topologies show no concentrationdependence in the investigated DNA concentration range (0.1 mM–0.4mM) and no structural change upon heating.