Fig. 4: Affinity characterization of MEDUSAs prepared with selected FNAPs.
a, SPR sensorgrams characterizing the binding kinetics between trimeric SARS-CoV-2 spike protein immobilized on the CM3 chip and mono-, di- and trivalent assemblies of selected FNAPs. RU, response units. As controls, assemblies prepared with non-modified (nm) and scrambled non-modified (snm) versions of the corresponding binding units were used. The concentrations of injected assemblies were 9, 18, 37, 75, 150 and 300 nM. The black curves represent the binding kinetics fit. b, SPR kinetic parameters (ka, association rate constant; kd, dissociation rate constant; Kd, dissociation constant) for trivalent supramolecular assemblies prepared using side-chain-deficient variants of m2 and m11 sequences. c, Competition ELISA assay indicates distinct binding specificity between FNAPs selected via multivalent and monovalent selection strategies. The assay was performed in duplicate (n = 2, technical replicates), and the mean values are plotted. d–f, Competition BLI sensorgrams depicting spike protein binding to dimeric ACE2-Fc, immobilized on the Protein A BLI probes. Assemblies of selected FNAPs (d, m1 MEDUSA; e, m2 MEDUSA, f, m11 MEDUSA) were mixed with trimeric SARS-CoV-2 spike protein at three increasing assembly concentrations. The decrease in mass transfer to the BLI probe indicates that the compound interferes with the ACE2–spike protein interaction. Assemblies of scrambled non-modified variants of the selected sequences were used as negative controls. The gradient triangle indicates the increasing concentration of FNAP assembly. All measurements were performed in duplicate (n = 2, technical replicates), and average signals were plotted with the s.d. range highlighted. NA, not applicable.
