From the Cover: Allosteric, chiral-selective drug binding to DNA -- Data Supplement - Supplemental Data -- Proceedings of the National Academy of Sciences

Supplementary material for Qu et al., Proc. Natl. Acad. Sci. USA, 10.1073/pnas.20221397

Table 3
. Binding parameters obtained with the neighbor-exclusion model for binding of daunomycin and WP900 bound to [poly (dGdC])₂.

Parameter*	Daunorubicin^†	WP900^‡
n , bp	2.3 ± 0.06	1.7 ± 0.06
K /10⁴M^–1	90.3 ± 4.9	6.6 ± 0.2

*Parameters n and K were obtained from nonlinear least-squares fits of experimental data to the neighbor-exclusion model:

r
/C = K(1-nr)((1-nr)/(1-(n-1)r))^(n-1)

where r is the ratio of bound drug to the total base pair concentration, C is the concentration of free drug, K is the binding constant to an isolated DNA lattice site, and n is the neighbor-exclusion parameter.

^†Daunomycin binding to [poly (dGdC)]₂ in buffered 2.1 M NaCl condition. Titration experiments required 45- to 60-min equilibration times following the addition of drugs because of the slow equilibration of the transition of B and Z form [Chaires, J. B. (1986) J. Biol. Chem. 261, 8899–8907]. Following the addition of drugs to [poly (dGdC)]₂, the fluorescence was continuously monitored at an appropriate fixed wavelength to ensure complete equilibration of the binding reactions. ^‡WP900 binding to [poly (dGdC)]₂ in buffered 3.0 M NaCl condition. Titration experiments were carried out as described in †.