The interaction between Berberine chloride with complex Histone(H1)- DNA by multi spectroscopic and molecular modeling

DNA is the primary target of many anticancer drugs .Based on the former studies any changes in DNA structure has an important impact on the interaction of DNA-histone H1 complex and consequently on intercellular processes especially transcriptional regulation, since histone H1 is known as the inhibitor of gene expression. Some small molecules bind to histone-DNA complex and impair the important processes such as cell division, growth,and thus they lead to apoptosis in cancer cells. Therefore the study of drug-histone (H1) DNA interaction is important for a better understanding of the mechanism of action and to design newer and more effective drugs.In this study, the interaction of histone-DNA complex and Berberine chloride was investigated in Tris buffer (pH 6.8) using fluorescence spectroscopy, resonans light scattering, transition temperature, viscometry, circular dichroism, UV-visible and molecular docking and MTT assay techniques.In fluorescence spectroscopy method emission reduction indicates quenching and complex formation that in a 351 excitation wavelength Berberine caused flourscence quenching of DNA, Histone H1 and DNA-Histone H1. In competitive emission espectrum interacation between ethidium bromide and acridine orange as intercalator probs with Berberine was studied and it was showed that the addition of the Berberine to DNA-Ethidium bromide and DNA-Acridine orange complexes ,causes change in emission spectra of the complexes which indicates competition but in presence of Histone this competition between the ligand and probes was not observed. So the competition between Berberine and intercalator probes represents that Berberine binds between DNA base pairs. In resonans light scattering by adding ligand to macromolecules the number of particles were increased so the spectra was increased. According to temperture transition studies adding Berberine to DNA increased DNA melting point and stability ,although melting point did not change in presence of Histone H1. In viscometry method, the viscosity of DNA was increased by adding compound to DNA solution which was due to intercalating interaction but in the presence of the histone H1, viscosity decreased.Also, due to intercalating compounds such as potassium iodide and sodium chloride ions, which compete with berberine chloride over binding sites in the absence of histone, it can be predicted that the Berberine binds between DNA base pairs. In circular dichroism by additing ligands separately to DNA two peaks in positive and negative areas were observed, but for DNA-H1 complex just one peak in negative area was observed which was falling to a more negative point. The results of the experiments showed that the type of Berberine interaction with DNA in absence of histone H1 is intercalation and in the presence of the histone Berberin binds to DNA grooves. Molecular docking also confirmed the above results.

کلیدواژه ها:

ct-DNA ، DNA-Histone ، Berberine ، Spectroscopy ، Molecular Docking