Effect of the binding interaction of an emissive niacin derivative on the conformation and activity of a model plasma protein: A spectroscopic and simulation-based approach.
The present work demonstrates a detailed photophysics of bio-active drug-like acid viz., 2-hydroxynicotinic acid (2-HNA) and its interaction with a model plasma protein Bovine Serum Albumin (BSA). The drug which is in essence a vitamin-B3derivative, is capable of exhibiting ultrafast lactim-lactam cross-over response and thereby the modulation of the lactam emission within the bio-environment of the protein has been depicted spectroscopically to reveal the drug-protein interaction. Apart from evaluating the binding constant, the probable location of the neutral drug molecule within the protein cavity (hydrophobic subdomain IIIA) has been explored by AutoDock-based blind docking simulation technique. In this microheterogeneous medium, slow solvent reorientation time with respect to the emissive lifetime of the drug explicate the Red Edge Effect (REE). To complement the findings about the binding process, chaotrope-induced protein denaturation has also been inspected. The probe also illustrates a perceptible difference in rotational relaxation time in confined medium than in aqueous medium which strengthen our verdict. Unfolding of the protein in the presence of the drug molecule has been probed by the decrease of the α-helical content, obtained via circular dichroism (CD) spectroscopy, which is also supported by the gradual slaughter of the esterase activity of the protein in the presence of the drug molecule.
Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Calcutta 700009, India.
Riya
R
Sett
Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Calcutta 700009, India.
Aniruddha
A
Ganguly
Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Calcutta 700009, India. Electronic address: nguchhait@yahoo.com.
Nikhil
N
Guchhait
D001798:Blood Proteins / Q000737:chemistry*; D009525:Niacin / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence
D001798:Blood Proteins; D009525:Niacin
Bovine serum albumin; Esterase activity; Red-edge-effect; Rotational relaxation; α-Helical content