Figure 6. The percent (%) unexchanged hydrogens vs. time (min) from FTIR of SP-C mimics in surfactant lipids.

SP-Css ion-lock 1 (inverted triangle, green), SP-C33 UCLA (square, magenta) and SP-Cff ion-lock 1 (hex, blue) were each incorporated into DPPC:POPC:POPG (5:3:2, weight ratio), and the peptide-lipid sample on the ATR crystal was initially hydrated by bubbling nitrogen through a 10 mM deuterated phosphate buffer (pD 7.4) at 37 °C. The time-dependent H/D exchange of the amide group was determined from the decay of the amide II band area (1525–1565 cm⁻¹) with respect to the corresponding amide I band area (∼1600–1700 cm⁻¹) as a function of time (0–6 h).