Nuclear spin-hyperpolarization generated in a flavoprotein under illumination: experimental field-dependence and theoretical level crossing analysis

Nuclear spin-hyperpolarization generated in a flavoprotein under illumination: experimental field-dependence and theoretical level crossing analysis Full article

Journal

Scientific Reports
ISSN: 2045-2322

Output data

Year: 2019, Volume: 9, Number: 1, Article number : 18436, Pages count : 11 DOI: 10.1038/s41598-019-54671-4

Authors

Ding Yonghong ¹ , Kiryutin Alexey S ^2,3 , Yurkovskaya Alexandra V. ^2,3 , Sosnovsky Denis V. ^2,3 , Sagdeev Renad Z. ^2,3 , Bannister Saskia ⁴ , Kottke Tilman ⁴ , Kar Rajiv K. ⁵ , Schapiro Igor ⁵ , Ivanov Konstantin L ^2,3 , Matysik Jörg ¹

Affiliations

1	Institut für Analytische Chemie, Universität Leipzig, Linnéstr. 3, 04103, Leipzig, Germany
2	International Tomography Center, Siberian Branch of Russian Academy of Sciences, Institutskaya, 3а, Novosibirsk, 630090, Russia
3	Novosibirsk State University, Pirogova 1, Novosibirsk, 630090, Russia
4	Physical and Biophysical Chemistry, Bielefeld University, Universitätsstr. 25, 33615, Bielefeld, Germany
5	Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel

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.

Ding Y. , Kiryutin A.S. , Yurkovskaya A.V. , Sosnovsky D.V. , Sagdeev R.Z. , Bannister S. , Kottke T. , Kar R.K. , Schapiro I. , Ivanov K.L. , Matysik J.
Nuclear spin-hyperpolarization generated in a flavoprotein under illumination: experimental field-dependence and theoretical level crossing analysis
Scientific Reports. 2019. V.9. N1. 18436 :1-11. DOI: 10.1038/s41598-019-54671-4

Submitted:	Sep 6, 2019
Accepted:	Nov 15, 2019
Published online:	Dec 5, 2019

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