Sánchez Torralba, AntonioColmenarejo, GonzaloMontero Carnerero, Francisco2025-01-292025-01-292001Torralba AS, Colmenarejo, G, Montero, F10.1002/1097-0282(200105)58:6<562::AID-BIP1031>3.0.CO;2-8https://hdl.handle.net/20.500.14352/116824A method for detecting and quantifying the cooperativity in the simultaneous binding of two ligands, A and B, to DNA (intercooperativity; ωAB) is proposed. This involves the determination of an apparent affinity constant Kapp for one of the ligands (A) in the limit of its null saturation (ν -> 0), in the presence of the second one (B). A definition for this constant is given and an expression is derived corresponding to a simple model of competitive binding to an unbranched three-state homogeneous polar lattice with nearest-neighbor interactions (Markov chain). The ratio between the apparent and intrinsic affinity constants of one ligand in the maximum saturation limit of the 2 other one becomes ωAB2, and thus can be graphically obtained from KAapp vs νB plots. All the frequencies that define the sequence distribution of ligands can be easily calculated by introducing some generalized statistical weights for the free lattice monomer in a standard sequence generating function procedure. A model of fluorescence quenching emission is obtained from such frequencies under the hypothesis of a short-range electron transfer mechanism of the deactivation; it confirms, as suggested by the binding model, an outstanding influence of the intercooperativity on the distribution.engAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/journal article1097-0282https://doi.org/10.1002/1097-0282(200105)58:6%3C562::AID-BIP1031%3E3.0.CO;2-811246205open accessBinding modelLigandsDNACooperativitySequence distributionElectron transferFluorescence emission quenchingMetal complexesBioquímica (Química)Química física (Química)2302 Bioquímica2307 Química Física