Copyright information:Taken from "Kinetics of double-chain reversals bridging contiguous quartets in tetramolecular quadruplexes"Nucleic Acids Research 2006;34(8):2386-2397.Published online 8 May 2006PMCID:PMC1458523.© The Author 2006. Published by Oxford University Press. All rights reserved () Melting profile of oligonucleotide in 0.11 M Na. Absorbance at 295 nm (crosses) or 240 nm (circles) is recorded every 4 min with a thermal gradient of ∼0.09°C/min in a pH 7.0, 10 mM sodium cacodylate buffer supplemented with 0.1 M NaCl. () Hysteresis in the denaturation/renaturation process of in 0.11 M Na at 20 µM strand concentration (temperature gradient 0.278°C/min). Arrows indicate directions of temperature changes. At this strand concentration, once melted, the tetramolecular quadruplex does not refold upon cooling, but a very slow renaturation is observed at 3°C after the cooling experiment. () of the (circles), (triangles) (squares) and (diamonds) quadruplexes as a function of the average temperature gradient. Note that the ‘true’ equilibrium , which would be obtained with an infinitely slow gradient cannot be approached by this method, only an upper limit may be determined. () Arrhenius plots for the dissociation of (black symbols), (red symbols) and TGT (squares; dotted line) quadruplexes. Different symbols (squares, crosses and so on) correspond to independent melting profiles recorded at 240 or 295 nm using different temperature gradients. () Effect of pH on for , d(GCGGGGAT, closed circles) and dTGT (red symbols). Values determined for a heating temperature gradient of 0.48°C/min. () Effect of ionic strength on for , d(GCGGGGAT, circles) and dTGT (red symbols). Values determined for a heating temperature gradient of 0.48°C/min. These experiments were performed in a 10 mM lithium cacodylate, pH 7.2, buffer with various concentrations of NaCl.