Purification and primary biophysical studies of the pre-core promoter wt, G1738A, G1748A, and G1738/1748A mutant oligomers.A, the change in size-exclusion chromatography (SEC) elution profile suggests change in size of G4s. B, circular dichroism spectroscopy studies of the pre-core promoter oligomers. The presence of a negative peak at ∼242 nm and a positive peak at ∼263 nm indicates that the G4s are present at a parallel quadruplex in the solution, the respective values are tabulated in Table S1. The plots represent the average of the three independent runs for each.