title: Microcalorimetric and spectrographic studies on the interaction of DNA with betaxolol.
abstract: The interaction of calf thymus deoxyribonucleic acid (ct-DNA) with betaxolol (BET) in aqueous buffer solution (pH 7.40) has been investigated using isothermal titration calorimetry (ITC), ultraviolet absorption (UV), fluorescence spectroscopy (FS) and circular dichroism (CD). Thermodynamic parameters, i.e., equilibrium constants, standard changes of enthalpy (DeltaH degrees ), Gibbs free energy (DeltaG degrees) and entropy (DeltaS degrees ), for the binding process of the drug to the bio-macromolecules have been derived from the calorimetric data. Analysis of the thermodynamic data indicates that there are two classes of binding sites on the DNA molecules being able to coordinate with BET molecules. One class of binding takes place at the sites formed by base pairs, which is synergistically driven by enthalpy and entropy, while the other one takes place on phosphate groups and shown as an entropy driven process. The thermodynamic behavior of the DNA-drug supramolecular system has been discussed in the light of the important weak interactions, hydrophobic force, hydrogen bond and electrostatic force, according to the UV, FS and CD spectra.
authors.affiliation: College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, Shandong Province, PR China. sundezhisdz@163.com
authors.forename: Dezhi
authors.initials: D
authors.lastname: Sun
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Xu
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Sun
authors.forename: Jingyu
authors.initials: J
authors.lastname: Zhang
authors.forename: Linwei
authors.initials: L
authors.lastname: Li
authors.forename: Youying
authors.initials: Y
authors.lastname: Di
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000737:chemistry*; D000818:Animals; D001599:Berberine / Q000737:chemistry; D015784:Betaxolol / Q000737:chemistry*; D001665:Binding Sites; D002021:Buffers; D002151:Calorimetry; D002417:Cattle; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D000319:Adrenergic beta-Antagonists; D002021:Buffers; D001599:Berberine; D004247:DNA; C427203:calf thymus DNA; D015784:Betaxolol