Fig. 3.

Crystal structure and stability of GR918.2. (A) GR918.2 crystal structure (gray) aligned to the design model (green) with a backbone RMSD of 1.33 Å. (B) At only 5.6 kDa, GR918.2 (gray) captures the functional beta sheet interface of the 11.6-kDa binding domain of PD-L2 (yellow). (C) CD spectra at an initial temperature of 25 °C (blue), after incubating at 95 °C for 10 min (orange), and then after cooling back down to 25 °C (gray). (D) Chemical denaturation with GuHCl, monitoring CD signal at 220 nm. MRE = molar residue ellipticity.