Scientists at McGill University in Canada have explained why older people are more vulnerable to the SARS-CoV-2 coronavirus. This is reported in an article published in the Computational and Structural Biotechnology Journal.
The researchers analyzed the amino acid sequences of proteins involved in the infection of cells with coronavirus. It turned out that coronavirus S-proteins and the cellular receptors ACE2 interacting with them are rich in cysteine residues (Cys). Many cysteine residues remain common to various SARS-related coronaviruses and are involved in the formation of intramolecular disulfide bonds.
These two bonds potentially have a redox potential, which facilitates the primary interaction between the receptor and the spike protein. This, in turn, enhances the pathogenesis and contributes to the development of severe symptoms of COVID-19. Coronavirus-resistant animals lack redox disulfide (Cys133-Cys141) in the ACE2 sequences, which confirms the hypothesis of the oxidative nature of the pathogenicity of the virus.
Thus, increased cellular oxidation with age is the most likely explanation for the increased vulnerability of the elderly and people with underlying medical conditions to COVID-19.