Detection of trivalent arsenic [As(III)] complex with DNA: A spectroscopic investigation

Abstract

Arsenite [As(III)] is well known to exert mutagenic or carcinogenic effects. Arsenic (III) binds proteins with its cystine–SH group to DNA. Overall binding constant K = 1.12 × 10⁴ M⁻¹ and exponential decay constant T ₁ = 271 s for DNA–As (III) interaction were measured spectrophometrically at λ _max = 260 nm. Fourier transform infrared (FTIR) spectrometric method was used to charac-terize and determine the arsenite binding site in DNA–As(III) interaction. FTIR spectroscopic results showed that As(III) indirectly binds to the nitrogen bases of DNA and predominantly affected the H-bonded OH and NH bands, whereas no interaction was found with phosphate groups. No transitions from B to A or B to Z was observed in B-DNA structure.

Keywords:

• DNA–As(III) interaction
• FTIR spectra
• optical absorption