TY - JOUR
T1 - Influence of Hyperfine Coupling Strain on Two-Dimensional ESEEM Spectra from I = 1/2 Nuclei
AU - Dikanov, Sergei A.
AU - Taguchi, Alexander T.
N1 - Publisher Copyright:
© 2020, Springer-Verlag GmbH Austria, part of Springer Nature.
PY - 2020/10/1
Y1 - 2020/10/1
N2 - HYSCORE, a variant of two-dimensional ESEEM spectroscopy, is currently one of the most effective tools in high-resolution solid-state EPR spectroscopy. Our systematic studies of hydrogen bonds with semiquinones in 15N-labeled proteins have previously provided us with an extensive collection of 15N HYSCORE spectra produced by N–H…O nitrogen donors. Examination of these spectra has indicated in several cases lineshape distortions not described by available theoretical models. We were able to explain all observed artificial phenomena in the 15N spectra of semiquinones considering a single mechanism—strain of the isotropic hyperfine interaction. In this review article, we introduce the HYSCORE experiment and the theoretical background for spectra of I = 1/2 nuclei in orientation-disordered samples. We then present a description of the observed lineshape distortions and an explanation of the hyperfine strain’s influence on the experimental spectra. In the final part of the article, we discuss (i) similar lineshape distortions found in previously published spectra from 15N, 29Si, 31P, and 57Fe nuclei that can be explained using the approach applied for the analysis of the 15N spectra of semiquinones, and (ii) a recently published analysis of 31P spectra with a different type of lineshape distortion based on a more sophisticated method, where the strength of anisotropic coupling is correlated with the sign and value of the isotropic constant in different conformations of a Cu(II) complex.
AB - HYSCORE, a variant of two-dimensional ESEEM spectroscopy, is currently one of the most effective tools in high-resolution solid-state EPR spectroscopy. Our systematic studies of hydrogen bonds with semiquinones in 15N-labeled proteins have previously provided us with an extensive collection of 15N HYSCORE spectra produced by N–H…O nitrogen donors. Examination of these spectra has indicated in several cases lineshape distortions not described by available theoretical models. We were able to explain all observed artificial phenomena in the 15N spectra of semiquinones considering a single mechanism—strain of the isotropic hyperfine interaction. In this review article, we introduce the HYSCORE experiment and the theoretical background for spectra of I = 1/2 nuclei in orientation-disordered samples. We then present a description of the observed lineshape distortions and an explanation of the hyperfine strain’s influence on the experimental spectra. In the final part of the article, we discuss (i) similar lineshape distortions found in previously published spectra from 15N, 29Si, 31P, and 57Fe nuclei that can be explained using the approach applied for the analysis of the 15N spectra of semiquinones, and (ii) a recently published analysis of 31P spectra with a different type of lineshape distortion based on a more sophisticated method, where the strength of anisotropic coupling is correlated with the sign and value of the isotropic constant in different conformations of a Cu(II) complex.
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U2 - 10.1007/s00723-020-01246-6
DO - 10.1007/s00723-020-01246-6
M3 - Review article
AN - SCOPUS:85089986583
SN - 0937-9347
VL - 51
SP - 1177
EP - 1200
JO - Applied Magnetic Resonance
JF - Applied Magnetic Resonance
IS - 9-10
ER -