The preference of SX3CX9C structures to 'drop out' upon bicyclization suggested that apart from the motif, the tolerance to modification also depends on the ring size. BLI measurements validated the 'drop out' and 'non-drop out' observations from NGS analysis. Two 'drop out' peptides predicted by NGS, SDLQCMDWDEAWPWC and SDFTCSGWGTGWHMC, had Kd = 25.4 nM and Kd =1.9 µM, and both peptides lost their binding affinity after Malins bicyclization. Meanwhile, a 'non-drop out' and HXDMT motif containing sequence SQVHCYHGDMTMPIC showed Kd = 21.0 nM before modification and Kd = 29.8 nM after Malins bicyclization (Figure ). Both forms of this peptide can be inhibited by grazoprevir (Figure ). In general, the combination of BLI and NGS analysis suggested that peptides with HXDMT motif have capacity to be reshaped into multiple forms while binding to NS3aH1 target.