Biophysical studies of the binding of histone deacetylase inhibitor (Trichostatin-A) with bovine serum albumin

Abstract

Trichostatin A (TSA), a potential radiomitigator in pre-clinical models, inhibits the class I and II mammalian histone deacetylase (HDAC) enzyme family preferentially. In the current study, the ADME assessment of TSA was explored in terms of its binding affinity for serum protein via spectroscopic and molecular docking techniques. Fluorescence spectroscopy was used to examine changes in the protein microenvironment, and affinity was quantified in terms of binding constant and stoichiometry. Post binding conformational changes were observed using circular dichroism (CD) and UV-Visible spectroscopy. Specific binding was visualized using molecular docking to support experimental studies. UV-vis spectra demonstrated a blue shift in the interaction of TSA to BSA. The calculated binding constants ranged from 3.10 to 0.78 x 10 5(M−1) and quenching constants from 2.75 to 2.15 x 104 (l mol-1), indicating TSA has a strong binding affinity for BSA. Based on the FRET theory, the distance between BSA (donor) and TSA (acceptor) was calculated to be 2.83 nm. The Stern-Volmer plot revealed (Ksv) static quenching. Thermodynamic parameters were calculated, and a negative ΔG value showed that the interaction is spontaneous. The CD spectra analysis further revealed a change in the protein’s secondary structure, indicating TSA-BSA interaction. The molecular docking studies also indicated strong binding affinity of TSA with BSA. The results indicate that good bio-availability of TSA is possible because of the spontaneous and strong binding affinity with BSA. Communicated by Ramaswamy H. Sarma