N-15-H-1 Transfer of Light-Induced Nuclear Hyperpolarization in Frozen Photosynthetic Reaction Centers

摘要

Recently, we have demonstrated the possibility to transfer the light-induced hyperpolarization occurring on select C-13 nuclei of photosynthetic cofactors due to the solid-state photochemically induced dynamic nuclear polarization (photo-CIDNP) effect into the proton pool via inverse C-13-H-1 cross-polarization Bielytskyi et al. (J Magn Reson 293: 82-91, 2018). Such approach allowed us to observe the selective response from the protons belonging to photochemically active cofactors in their native protein environment. In the present study, we demonstrate that also N-15 nuclei can be used as a source of polarization in a similar type of experiments. We present the 2D photo-CIDNP N-15-H-1 heteronuclear correlation (HETCOR) experiment acquired on uniformly N-15-labeled quinone-blocked reaction center (RC) from Rhodobacter sphaeroides R26. Obtained H-1 chemical shifts match with previously observed ones on selectively C-13-labeled RC from Rhodobacter sphaeroides WT. We expect that using N-15 as a source of polarization in potential heteronuclear spin-torch experiments could be advantageous for systems where the procedure for selective C-13 labeling is not yet established.