Fig. 8: Hyperpolarized CEST experiments for the identification of reaction intermediates.
PHIP-CEST experiments performed at 309 K and 14.1 T (600 MHz), with sample conditions as for Fig. 2. a, The HD-PHIP-CEST profile obtained from multiple quantum-filtered experiments (Supplementary Fig. 7), using an 8 s saturation with γB1 = 666 Hz (γ, gyromagnetic ratio). The HD signal integral, normalized to the off-resonance integral, measured at −36 ppm, is shown in orange. Data from five samples were averaged, collecting one single-scan spectrum per offset and per sample. The error bars indicate s.d. A simulated HD-PHIP-CEST profile (Supplementary Discussion and Supplementary Table 12) is overlaid. In grey, the ranges of computed chemical shifts (δCALC) for hydrogen species obtained from multiple different QM/MM models (Supplementary Discussion and Supplementary Tables 13–16) are indicated. b, The H2-PHIP-CEST experiment according to Supplementary Fig. 6, using a 2 s saturation with γB1 = 1,333 Hz. The H2 lineshape observed after irradiating at different offsets and the corresponding H2 line integral (polarization × concentration), normalized by sample activity for hydrogen isotope exchange (activity range of 68–41 U mg−1). The average from three samples is shown with s.d. as error bars. A simulated profile obtained using the same simulation parameters as in a is shown in green. Simulated data are upscaled tenfold for better visualization of the qualitative agreement obtained.
