These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
4 files

N-acetyl cysteine: A tool to perturb SARS-CoV-2 spike protein conformation

revised on 05.01.2021, 15:41 and posted on 06.01.2021, 05:54 by Utsab Debnath, Amrita Mitra, Varun Dewaker, Yenamandra S. Prabhakar, Raghu Tadala, Kiran Krishnan, Padmakar Wagh, Umashankar Velusamy, Chandru Subramani, Shubhra Agarwal, Sudhanshu Vrati, Aastha Baliyan, Anura V Kurpad, Parthasarathi Bhattacharyya, Amit Mandal

The infection caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) resulted in a pandemic with huge death toll and economic consequences. The virus attaches itself to the human epithelial cells through noncovalent bonding of its spike protein with the angiotensin-converting enzyme-2 (ACE2) receptor on the host cell. We hypothesized that perturbing the functionally active conformation of spike protein through reduction of its solvent accessible disulfide bond, thereby disintegrating its structural architecture, may be a feasible strategy to prevent infection. Proteomics data showed that N-acetyl cysteine (NAC), an antioxidant and mucolytic agent been widely in use in clinical medicine, forms covalent conjugates with solvent accessible cysteine residues of spike protein that were disulfide bonded in the native state. In silico analysis indicated that this covalent conjugation perturbed the stereo specific orientations of the interacting key residues of spike protein that resulted in threefold weakening in the binding affinity of spike protein with ACE2 receptor. Antiviral assay using VeroE6 cells showed that NAC caused 54.3% inhibition in SARS-CoV-2 replication. Interestingly, almost all SARS-Cov-2 variants conserved cystine residues in the spike protein. Our observed results open avenues for exploring in vivo pharmaco-preventive and therapeutic potential of NAC for Coronavirus Disease 2019 (COVID-19).


Email Address of Submitting Author


Department of Biological Science, Indian Institute of Science Education and Research Kolkata



ORCID For Submitting Author


Declaration of Conflict of Interest

No conflict of interest