Curious Pressure Dependence of the Stability of d(TGnT)
Ujala N. Feroze · TSpace (University of Toronto) · 2018
Monomolecular guanine-rich four-stranded DNA molecules (G-quadruplexes) are destabilized by hydrostatic pressure. These G-quadruplexes (GQ) are made up of loops (non-guanine regions) and tetrads (guanine-rich regions). The molar volume change (∆V total) of monomolecular GQ is the difference in the molar volume of the unfolded and folded states. We studied the effect of pressure on tetramolecular GQs because they have no “loops". From this, we determined the ∆V of each G-tetrad and the ∆V of the loops in monomolecular GQ. Our data show that there is no net molar ∆V between the folded and unfolded states of d(TG3-4T)4. Furthermore, the ∆V is unrelated to the parallel orientation of the strands in d(TG3-4T)4. Therefore, the factors causing the ∆V arising from the formation of tetramolecular GQ balance each other resulting in the net ∆V as zero. Thus, the ∆V values in monomolecular GQ are due to the “loop” regions of those structures.