Binding of anti-inflammatory drug cromolyn sodium to bovine serum albumin

• Published in: International journal of biological macromolecules Vol. 39; no. 4; pp. 280 - 285
• Main Authors: Hu, Yan-Jun, Liu, Yi, Sun, Ting-Quan, Bai, Ai-Min, Lü, Jian-Quan, Pi, Zhen-Bang
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.11.2006
• Subjects: Animals; Anti-Inflammatory Agents, Non-Steroidal - chemistry; Anti-Inflammatory Agents, Non-Steroidal - metabolism; Anti-Inflammatory Agents, Non-Steroidal - pharmacology; Bovine serum albumin; Cattle; Circular Dichroism; Cromolyn sodium; Cromolyn Sodium - chemistry; Cromolyn Sodium - metabolism; Cromolyn Sodium - pharmacology; Energy Transfer; Fluorescence quenching; In Vitro Techniques; Protein Binding; Protein Conformation - drug effects; Serum Albumin, Bovine - chemistry; Serum Albumin, Bovine - drug effects; Serum Albumin, Bovine - metabolism; Spectrophotometry; Spectrophotometry, Ultraviolet; Thermodynamics; Cromolyn sodium; Bovine serum albumin; Fluorescence quenching; Circular dichroism
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2006.04.004

Fluorescence spectroscopy in combination with circular dichroism (CD) and UV–vis absorption spectroscopy were employed to investigate the binding of anti-inflammatory drug cromolyn sodium (Intal) to bovine serum albumin (BSA) under the physiological conditions with Intal concentrations of 0–6.4 × 10 −5 mol L −1. In the mechanism discussion, it was proved that the fluorescence quenching of BSA by Intal is a result of the formation of Intal–BSA complex. Quenching constants were determined using the Stern–Volmer equation to provide a measure of the binding affinity between Intal and BSA. The thermodynamic parameters Δ G, Δ H, Δ S at different temperatures (298, 304, and 310 K) were calculated and the results indicate the electrostatic interactions play a major role in Intal–BSA association. Binding studies concerning the number of binding sites ( n = 1) and apparent binding constant K b were performed by fluorescence quenching method. Utilizing fluorescence resonant energy transfer (FRET) the distance R between the donor (BSA) and acceptor (Intal) has been obtained. Furthermore, CD and synchronous fluorescence spectrum were used to investigate the structural change of BSA molecules with addition of Intal, the results indicate that the secondary structure of BSA molecules was changed in the presence of Intal.