the number and percentage of hydrogen bond formation between the ten individual residues of the substrate and those of the NS2B and NS3pro proteins were probed using the two following criteria: (i) a proton donor-acceptor distance of ≤3.5 Å, and (ii) a donor-H-acceptor bond angle of ≥120°. The number of strong, medium and weak hydrogen bond interactions was determined using hydrogen bond occupations of ≥80%, 50–79% and