Insights on Aggregation of Hen Egg-White Lysozyme from Raman Spectroscopy and MD Simulations
Divya Chalapathi,
Amrendra Kumar,
Pratik Behera,
Shijulal Nelson Sathi,
Rajaram Swaminathan,
Chandrabhas Narayana
Affiliations
Divya Chalapathi
Chemistry and Physics of Materials Unit, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru 560064, India
Amrendra Kumar
Department of Bioscience and Bioengineering, Indian Institute of Technology-Guwahati, North Amingaon, Guwahati 781039, India
Pratik Behera
Transdisciplinary Biology Program, Rajiv Gandhi Centre for Biotechnology, Thycaud Post, Poojapura, Thiruvananthapuram 695014, India
Shijulal Nelson Sathi
Transdisciplinary Biology Program, Rajiv Gandhi Centre for Biotechnology, Thycaud Post, Poojapura, Thiruvananthapuram 695014, India
Rajaram Swaminathan
Department of Bioscience and Bioengineering, Indian Institute of Technology-Guwahati, North Amingaon, Guwahati 781039, India
Chandrabhas Narayana
Chemistry and Physics of Materials Unit, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru 560064, India
Protein misfolding and aggregation play a significant role in several neurodegenerative diseases. In the present work, the spontaneous aggregation of hen egg-white lysozyme (HEWL) in an alkaline pH 12.2 at an ambient temperature was studied to obtain molecular insights. The time-dependent changes in spectral peaks indicated the formation of β sheets and their effects on the backbone and amino acids during the aggregation process. Introducing iodoacetamide revealed the crucial role of intermolecular disulphide bonds amidst monomers in the aggregation process. These findings were corroborated by Molecular Dynamics (MD) simulations and protein-docking studies. MD simulations helped establish and visualize the unfolding of the proteins when exposed to an alkaline pH. Protein docking revealed a preferential dimer formation between the HEWL monomers at pH 12.2 compared with the neutral pH. The combination of Raman spectroscopy and MD simulations is a powerful tool to study protein aggregation mechanisms.
