TY - JOUR

T1 - Nuclear spin-hyperpolarization generated in a flavoprotein under illumination

T2 - experimental field-dependence and theoretical level crossing analysis

AU - Ding, Yonghong

AU - Kiryutin, Alexey S.

AU - Yurkovskaya, Alexandra V.

AU - Sosnovsky, Denis V.

AU - Sagdeev, Renad Z.

AU - Bannister, Saskia

AU - Kottke, Tilman

AU - Kar, Rajiv K.

AU - Schapiro, Igor

AU - Ivanov, Konstantin L.

AU - Matysik, Jörg

PY - 2019/12/1

Y1 - 2019/12/1

N2 - The solid-state photo-chemically induced dynamic nuclear polarization (photo-CIDNP) effect generates non-equilibrium nuclear spin polarization in frozen electron-transfer proteins upon illumination and radical-pair formation. The effect can be observed in various natural photosynthetic reaction center proteins using magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, and in a flavin-binding light-oxygen-voltage (LOV) domain of the blue-light receptor phototropin. In the latter system, a functionally instrumental cysteine has been mutated to interrupt the natural cysteine-involving photochemistry allowing for an electron transfer from a more distant tryptophan to the excited flavin mononucleotide chromophore. We explored the solid-state photo-CIDNP effect and its mechanisms in phototropin-LOV1-C57S from the green alga Chlamydomonas reinhardtii by using field-cycling solution NMR. We observed the 13C and, to our knowledge, for the first time, 15N photo-CIDNP signals from phototropin-LOV1-C57S. Additionally, the 1H photo-CIDNP signals of residual water in the deuterated buffer of the protein were detected. The relative strengths of the photo-CIDNP effect from the three types of nuclei, 1H, 13C and 15N were measured in dependence of the magnetic field, showing their maximum polarizations at different magnetic fields. Theoretical level crossing analysis demonstrates that anisotropic mechanisms play the dominant role at high magnetic fields.

AB - The solid-state photo-chemically induced dynamic nuclear polarization (photo-CIDNP) effect generates non-equilibrium nuclear spin polarization in frozen electron-transfer proteins upon illumination and radical-pair formation. The effect can be observed in various natural photosynthetic reaction center proteins using magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, and in a flavin-binding light-oxygen-voltage (LOV) domain of the blue-light receptor phototropin. In the latter system, a functionally instrumental cysteine has been mutated to interrupt the natural cysteine-involving photochemistry allowing for an electron transfer from a more distant tryptophan to the excited flavin mononucleotide chromophore. We explored the solid-state photo-CIDNP effect and its mechanisms in phototropin-LOV1-C57S from the green alga Chlamydomonas reinhardtii by using field-cycling solution NMR. We observed the 13C and, to our knowledge, for the first time, 15N photo-CIDNP signals from phototropin-LOV1-C57S. Additionally, the 1H photo-CIDNP signals of residual water in the deuterated buffer of the protein were detected. The relative strengths of the photo-CIDNP effect from the three types of nuclei, 1H, 13C and 15N were measured in dependence of the magnetic field, showing their maximum polarizations at different magnetic fields. Theoretical level crossing analysis demonstrates that anisotropic mechanisms play the dominant role at high magnetic fields.

KW - STATE PHOTO-CIDNP

KW - BLUE-LIGHT RECEPTOR

KW - PHOTOSYNTHETIC REACTION CENTERS

KW - RHODOBACTER-SPHAEROIDES R26

KW - MAS NMR

KW - LOV2 DOMAIN

KW - ELECTRONIC-STRUCTURE

KW - ATOMIC-RESOLUTION

KW - C450A MUTANT

KW - SPECIAL PAIR

UR - http://www.scopus.com/inward/record.url?scp=85075967857&partnerID=8YFLogxK

U2 - 10.1038/s41598-019-54671-4

DO - 10.1038/s41598-019-54671-4

M3 - Article

C2 - 31804538

AN - SCOPUS:85075967857

VL - 9

JO - Scientific Reports

JF - Scientific Reports

SN - 2045-2322

IS - 1

M1 - 18436

ER -