Fluorophotometric Study on the Interaction of Bovine Serum Albumin with Amaranth in the Presence of Metal Ions of Cu(Ⅱ), Pb(Ⅱ) and Ni(Ⅱ)

Fluorophotometric study on the interation of bovine serum albumin (BSA) with amaranth (AT) in the presence of Cu(Ⅱ), Pb(Ⅱ) and Ni(Ⅱ) was made in a B-R buffer medium of pH 7.43 with λex and λem at 280 nm and 350 nm respectively. It was found that: ① due to binding with AT, quenching of intrinsic fluorescence of BSA was observed, and magnitude of the fluorescence quenching increased with increase of concentration of AT; ② upon addition of each of the 3 cations, fluorescence quenching of the reaction system of BSA-AT was enhanced at various extents; ③ each of the 3 cation take competition with AT to react with BSA to form mainly groud-state coordination complex of non-emission fluorescence, attributing to static quenching process, which enhanced the fluorescence quenching without changing the type of reaction. Non-radiative energy transfer happened to take place simultaneously with the quenching reaction, and ④ binding force of Pb(Ⅱ) with BSA hehaved to be stronger than the other 2 cations.