Hypochlorous acid induced structural and conformational modifications in human DNA: A multi-spectroscopic study.

Hypochlorous acid (HOCl) is generated by activated phagocytes at the site of inflammation. Exposure of DNA to HOCl results in base and nucleotide modifications causing DNA damage, which is one of the leading causes of various pathological conditions including carcinogenesis. In the present work, various biophysical techniques were used to study HOCl induced structural and conformational changes in human placental DNA. The HOCl modified DNA showed hyperchromicity, reduced fluorescence and decrease in melting temperature. Circular dichorism (CD) and Fourier transform infra-red (FT-IR) studies exhibited conformational changes and shift in band positions of DNA, respectively, suggesting structural changes. Agarose gel electrophoresis and scanning electron microscopy showed strand breakage and decreased aggregation. These results suggest that HOCl causes conformational and structural perturbations in mammalian DNA, which may consequentially lead to DNA mutations resulting in perturbation of epigenetic signals leading to cancer and autoimmune diseases.