Spectrofluorimetric study on the interaction between antimicrobial drug sulfamethazine and bovine serum albumin

► Fluorescence data was used to demonstrate that BSA fluorescence can be quenched by STM. ► STM can bind to BSA with stoichiometric ratio of 1:1. ► STM-BSA complex is stabilized mainly by hydrogen bonds and van der Waals interaction. ► Synchronous fluorescence data revealed that BSA undergoes conformational changes upon binding to STM. ► The distance between STM and Trp. 213 was estimated to be 2.73 nm, which in turn indicates that STM can bind to BSA with high probability.