Study of the combination reaction between drugs and bovine serum albumin with methyl green as a fluorescence probe

We studied the combination between seven kinds of drugs and the bovine serum albumin (BSA) using Methyl Green (MG) as fluorescent probe. These drugs were Streptomycin sulphate, Kanamycin sulfate, Gentamicin, Amikacin, Neomycin, Thiamphenicol and Florfenicol. And after reaction of these drugs, the fluorescence intensity of BSA had no obvious change. Research has shown that in Tris-HCl (pH=7.40) buffer solution, MG made BSA fluorescence quenching, quenching mechanism belongs to static quenching, and the binding constant, binding points and interaction force type between MG and BSA were obtained under different temperature. Fluorescence intensity of BSA was recovered when seven kinds of drugs were added to the BSA-MG system, respectively. The degree of recovery were SM> AM> FN> TN> KM> GM> NM. This suggested that the reaction mechanism between MG, drugs and BSA was competition binding reaction, and the binding sites between seven kinds of drugs and BSA were determined on sub-domain IIA (site I) using labeled drugs with specific binding sites.