Deciphering the interaction of tetrabenazine with lactoferrin: Insights from molecular dynamics and multi-spectroscopic approaches.

Lactoferrin (LTF) is an iron-binding glycoprotein that has gained increasing attention in therapeutics for neurodegenerative diseases worldwide. This can be owed to its ability to cross the blood-brain barrier and modulate oxidative stress and inflammation. The present study explores the interaction of tetrabenazine (TBZ), an FDA-approved drug for Huntington's disease, with LTF using an integrated computational and experimental approach. The results from molecular docking analysis demonstrated that TBZ preferentially occupies the iron-binding pocket of LTF, forming key interactions with key residues, namely Arg108 and Arg229. Further, an extensive 300 ns molecular dynamics simulation (MD) was carried out to have an atomistic insight into the binding dynamics of the LTF-TBZ complex, with results depicting that binding of TBZ stabilizes the protein without inducing any major conformational changes. Computational observations were validated by experimental approaches. Fluorescence spectroscopy showed a concentration-dependent quenching of intrinsic tryptophan fluorescence, with a high binding constant (2.5 × 107 M-1), indicating strong affinity between TBZ and LTF. Circular dichroism (CD) analysis showed moderate alterations in secondary structure, with a reduction in α-helical content upon TBZ binding, implicative of conformational changes in LTF. Overall, our findings provide molecular-level insights into the binding mechanism and structural consequences of TBZ interaction with lactoferrin. This study highlights the potential of drug repurposing strategies to modulate protein function and offers a foundation for further exploration of LTF-targeted therapeutic interventions in neurodegenerative diseases.