Elucidation of binding mechanism and identification of binding site for an anti HIV drug, stavudine on human blood proteins

Biochemical aspects of hemoglobin-xenobiotic interactions and their implications in drug discovery

Hemoglobin, a homodimeric globular protein, is found predominantly in red blood cells and in a small amount in blood plasma. Along with binding to certain native molecules, it also interacts with various xenobiotics. The present review aims at studying these interactions and the resultant tangible impact on the structure and function of the protein if any. The review also encompasses various analytical and computational approaches which are routinely used to study these interactions. A detailed discussion on types of interaction exhibited by individual xenobiotics has been included herein. Additionally, the effects of xenobiotic binding on the oxygen carrying capacity of hemoglobin have been reviewed. These insights would be of great value in drug design and discovery. Envisaging probable interactions of designed ligands with hemoglobin would help improvise the process of drug development. This would also open up new avenues for studying hemoglobin-mediated drug delivery.

Biophysical insights into the interaction of hen egg white lysozyme with therapeutic dye clofazimine: modulation of activity and SDS induced aggregation of model protein

The present study details the binding process of clofazimine to hen egg white lysozyme (HEWL) using spectroscopy, dynamic light scattering, transmission electron microscopy (TEM), and molecular docking techniques. Clofazimine binds to the protein with binding constant (K_b) in the order of 1.57 × 10⁴ at 298 K. Binding process is spontaneous and exothermic. Molecular docking results suggested the involvement of hydrogen bonding and hydrophobic interactions in the binding process. Bacterial cell lytic activity in the presence of clofazimine increased to more than 40% of the value obtained with HEWL only. Interaction of the drug with HEWL induced ordered secondary structure in the protein and molecular compaction. Clofazimine also effectively inhibited the sodium dodecyl sulfate (SDS) induced amyloid formation in HEWL and caused disaggregation of preformed fibrils, reinforcing the notion that there is involvement of hydrophobic interactions and hydrogen bonding in the binding process of clofazimine with HEWL and clofazimine destabilizes the mature fibrils. Further, TEM images confirmed that fibrillar species were absent in the samples where amyloid induction was performed in the presence of clofazimine. As clofazimine is a drug less explored for the inhibition of fibril formation of the proteins, this study reports the inhibition of SDS-induced amyloid formation of HEWL by clofazimine, which will help in the development of clofazimine-related molecules for the treatment of amyloidosis.