Figure 3. ¹H-¹⁵N HSQC spectra of uniformly ¹⁵N labeled OmpX^M.

(A) Spectrum of OmpX^M refolded in 150 mM 60PC acquired on a 500 MHz spectrometer using conditions reported earlier [19]. Inset illustrates the ribbon diagrams of OmpX^HN (grey) and OmpX^M (slate) with the methionines of OmpX^HN and the corresponding leucines of OmpX^M highlighted. The OmpX^M structure was generated by homology modeling using I-TASSER [64], with Met residues at positions18, 21, 118 replaced by Leu residues, and 1QJ8 [18] as the starting template. (B) Overlay of the ¹H-¹5N HSQC spectra of OmpX^HN (black) and OmpX^M (red), highlighting similar resonance distribution between both the proteins. The OmpX^HN spectrum is adapted from [14].