In vitro interaction between calf thymus DNA and Escherichia coli LPS in the presence of divalent cation Ca2

摘要: With increasing addition of Escherichia coli LPS to calf thymus DNA, both dissolved in CaCl2, absorption maxima DNA at 260 nm decreased gradually with the appearance isosbastic points ends spectra, which implied some binding between and LPS. Hill plot absorbance data showed that interaction was positive cooperative nature. For any fixed concentration LPS, extent increased as CaCl2 raised from 1.0 100 mM, signifying electrostatic nature interaction, mediated through Ca2+ ion. Stepwise EDTA, a chelating agent for divalent cations, DNA-LPS bound complex reversed spectral shift increase nm, opening up complex, is, reversible interaction. Circular dichroism changes by indicated partial transition B A form. Isothermal titration calorimetric (ITC) study an exothermic enthalpy-driven phenomenon. Moreover, presence mM constant found be 2.6 x 10(4) M(-1) 3.1 analysis ITC result, respectively. DNA-melting had melting temperature indicating more stabilization double helix. The made resistant digestion endonucleases EcoRI DNase I.