An electrochemical analysis of the interaction of double-stranded DNA (dsDNA) with bovine serum albumin (BSA) as model protein was carried out. A decrease in the electrochemical oxidation peak current of DNA nucleobases was evaluated in the DNA-BSA complex at a BSA concentrations above 0.1 mu M, which indicated compaction of the DNA structure with a formation of partial clew and shielding of guanine, adenine, and thymine available for electrode reactions. At a BSA concentration below 0.1 mu M in DNA-BSA complex, an increase in the intensity of heterocyclic bases electro oxidation was observed, indicating partial unwinding of the DNA double strand. Using a calorimetric assay, the enthalpy of Delta H = + 2620.4 J/g was registered for DNA-BSA complex with low BSA concentration (below 0.1 mu M), and Delta H = + 82.7 J/g for high BSA concertation (above 0.1 mu M). The binding constants of the DNA-BSA complex based on adenine and thymine electrochemical signals were Kb = 4.52 x 106 M- 1 and Kb = 3.99 x 106 M- 1, respectively. The spectral binding constant of the DNA-BSA complex was determined as an integral parameter and corresponded to Kb = 3.98 x 106 M- 1, which in good agreement with electrochemical Kb values.
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