Determination of SARS-CoV-2 main protease (M<sup>pro</sup>) activity based on electrooxidation of the tyrosine residue of a model peptide

The proposed approach for determining the catalytic activity of SARS-CoV-2 main protease (Mpro) is based on the registration of the peak area of the electrochemical oxidation of the tyrosine residue of the model peptide substrate CGGGAVLQSGY immobilized on the surface of a graphite screen-printed electrode (SPE) modified with gold nanoparticles (AuNP). The AuNP were obtained by electrosynthesis. The steady state kinetic parameters of Mpro towards the model peptide were determined: catalytic constant (kcat) was (3.1 ± 0.1)·10–3 s–1; Michaelis constant (KM) was (358 ± 32)·10–9 M; catalytic efficiency (kcat/KM) was 8659 s–1/M. The limit of detection (LOD) determined for Mpro using the proposed electrochemical system was 44 nM. The proposed approach is a promising tool to search for new Mpro inhibitors as drugs for the treatment of coronavirus infections.