As predicted, AbHV2BD cyclic bound to OpaB variants better than Opa-negative variants (Figure 3E).
AbSV cyclic bound a greater number of different Opa variants than AbSV linear, including variants that differed by seven amino acids.
AbSV cyclic bound the same set of Opa variants as recognized in the SBI assay, but not OpaC or Opa-negative variants (Table 1).
AbSV cyclic bound OpaB variants well in the SBI and IFA assay, and we therefore assessed the capacity of AbSV cyclic and AbHV2BD cyclic to passively protect mice from OpaB variants.
AbSV cyclic bound intact OpaA, OpaB, OpaD, OpaF, OpaK and OpaI variants above background in the SBI assay at a dilution of 1∶40, while OpaC, OpaE, and Opa-negative variants were not recognized by AbSV cyclic (Figure 3D).
AbSV cyclic agglutinated OpaA and OpaB variants but not OpaK variants at a titer of 1∶12.5 compared to NMS (Figures 4C and D) although AbSV cyclic bound OpaK variants.
Both cyclic nucleotides bind to the protein through strong enthalpy driving forces, with enthalpy values of −12.5 versus −12.4 kcal/mol at 30°C, suggesting that binding is driven by charge-charge interactions, most likely between the phosphate groups and the highly charged residues of the PBC.
Furthermore, in contrast to IgG1, the cyclic peptides bind FcγRI specifically among the FcγR classes (Fig. 5), a result consistent with the modeling data where at least one of two conformers is disadvantaged for FcγRIII recognition.
A linear RGD bound primarily to β3 integrins, whereas a cyclic RGD bound through both β1 and β3 integrins.
We establish that, relative to the linear peptide, the cyclic one binds stronger to negatively charged membranes.
