Model of cooperative interaction of TMPyP4 porphyrine with DNA quadruplex

Intrinsic binding constants of the TMPyP4 porphyrin with G-quadruplex of DNA (ckit2) have been calculated; they can be applied as reference for quantitative evaluation of the possibility of such structures participation in biochemical processes. The conclusion about existence of two different sites of the TMPyP4 binding to ckit2 binding made earlier on the basis of the stepwise complex formation model has been revised using the model of mutual influence (cooperativity) of the ligands bound to the oligonucleotide. The model has been verified using principal component analysis and factor analysis methods. The ckit2 biomolecule can be considered as an oligonucleotide with equivalent mutually affecting binding sites.