Time course of deuterium incorporation into backbone amides in regions of RIα(91–244) subunit in C·RIα(91–244) in absence (○) and presence of (Rp)-cAMPS (●) for peptides. A, m/z = 797.86, z = 2 (residues 136–148). B, m/z = 846.89, z = 2 (residues 157–172). C, m/z = 567.32, z = 2 (residues 202–212). D, m/z = 523.81, z = 2 (residues 230–238). The solid lines denote the best fit of the data to a single exponential equation. Error bars were calculated from 2 replicate experiments.