Effects of D-RyR-Peptide on calcium affinity of WT and V91G D-CaM. Calcium titrations of D-CaM in the presence of D-RyR-Peptide as monitored by changes in (A) phenylalanine fluorescence (λex, 250 nm; λem, 280 nm), WT (filled circles), and V91G (open circles) D-CaM, and (B) tyrosine fluorescence (λex, 277 nm; λem, 320 nm), WT (filled squares), and V91G (open squares) D-CaM. Dashed curves represent the titration of WT D-CaM in the absence of D-RyR-Peptide.