Figure 4.
Spectroscopic properties of the M12/JRA complex (note: pH titration and pKa traces for all other mutants are provided in the SI, Figures S1–S12). a. PSB formation of M12 with JRA, with an apparent half-life of 35 sec is complete within 2 min at room temperature. b. The M12/JRA complex has a pH-dependent 75 nm wavelength shift in absorption. c. Emission intensity decreases in response to decreasing pH for excitation at 594 nm. d. Emission intensity increases in response to decreasing pH for excitation at 633 nm. e. pKa titration curve for M12. f. Standard curve of emission ratio (excitation at 594 nm and 633 nm)as a function of pH, leading to a ratiometric pH measurement.