Table 2. Entropic stabilization of folded guanine quadruplexes by G-register exchange.

	VEGFA	c-myc Pu18	PIM1
Number of GR isomers (N)	2	4	12
ΔΔStheo= Rln(N) J mol−1 K−1a	5.8	11.5	20.7
ΔΔSexp J mol−1 K−1b	5.20 ± 0.01	6.2 ± 0.9	14.3 ± 1.6
KF,exch/KF,indivc	1.8 ± 0.1	2.1 ± 0.5	4.5 ± 1.9
ΔTm°Cd	3.1 ± 0.3	3.4 ± 1.2	7.3 ± 1.6

Parameters given here are the average of the results from dT and dI trapped mutant data sets where applicable (DSC and UV-Vis for c-myc Pu18, UV-Vis for PIM1).

^aMaximum conformational entropy contribution for exchange among N isomers.

^bActual conformation entropy contribution calculated using trapped mutant populations at 25°C.

^cRatios of wild-type and most-populated trapped mutant folding equilibrium constants evaluated at the wild-type T_m.

^dWild-type thermal upshifts relative to the most-populated GR isomer. Errors were calculated as the standard deviations of the values extracted from global fits of DSC and UV-Vis data according to variance/co-variance method (See Supplementary Methods).