Spectroscopic study on interaction between bovine hemoglobin and salmon DNA and the analytical applications

In weak acidic medium, bovine hemoglobin would bind with salmon DNA (sDNA) to form a complex. This resulted in changes of absorption and circular dichroism spectra, fluorescence quenching of hemoglobin and remarkable enhancement of resonance Rayleigh scattering (RRS), as well as the appearance of a new RRS spectrum. The spectral characteristics of these spectra were investigated. The type of fluorescence quenching was discussed via the fluorescence lifetime of hemoglobin before and after the reaction as well as effects of temperature on fluorescence intensity. The conformational change of bovine hemoglobin was explored through circular dichroism spectra. The reasons of RRS enhancement were also discussed. In addition, it was found that the fluorescence quenching and RRS methods using bovine hemoglobin as a probe could be used to the determination of DNA. The detection limits (3σ) for sDNA were 5.5 ng mL−1 (RRS method) and 202.3 ng mL−1 (fluorescence quenching method). The optimum reaction conditions of the two methods were tested. The selectivity of RRS method was examined owing to its higher sensitivity. The RRS method was used for the determination of DNA in synthetic samples with satisfactory results.