Study on the interaction between florasulam and bovine serum albumin

In this paper, the interaction between florasulam ( FU, 2', 6', 8- trifluoro- 5- methoxy [ Kragh- Hansen U, Molecular aspects of ligand binding to serum albumin. Pharmacol Rev 33 ( 1): 17 - 53 1981; Carter DC and Ho JX, Structure of serum albumin. Adv Protein Chem 45: 153 - 203 1994; He XM, and Carter DC, Atomic structure and chemistry of human serum albumin. Nature 358( 6383): 209 - 215 1992] triazolo [ 1,5- c] pyrimidine-2-sulfonanilide) and bovine serum albumin ( BSA) was investigated by fluorescence, ultraviolet absorption ( UV) and Far-UV circular dichroism ( CD) spectrometries. A strong fluorescence quenching was observed and the quenching mechanism was considered as static quenching. The binding constant of FU with BSA at 299 and 309 K were obtained as 1.5 x 10(4) and 7.1 x 10(3) l mol(-1), respectively. There was one binding site between FU and BSA. The thermodynamic parameters enthalpy change (Delta H) and entropy change (Delta S) were calculated as - 57.89 kJ mol(-1) and - 113.6 J mol(-1) K-1, respectively, which indicated that the acting force between FU and BSA was mainly hydrogen bond and Van der Waals force. According to the Forster non-radiation energy transfer theory, the average binding distance between donor ( BSA) and acceptor ( FU) was obtained ( r= 1.59 nm). The investigations of the UV/Vis and CD spectra of the system