Statistical analysis of ENDOR spectra
| Autor: | JoAnne Stubbe, Stephan Huckemann, Igor Tkach, Marina Bennati, Benjamin Eltzner, Markus Hiller, Clemens Beeken, Yvo Pokern |
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| Rok vydání: | 2021 |
| Předmět: |
Statistics as Topic
statistical tests 010402 general chemistry 01 natural sciences Molecular physics Spectral line law.invention tyrosyl radical law Ribonucleotide Reductases Escherichia coli Computer Simulation Amino Acids bootstrap Electron paramagnetic resonance Spectroscopy Hyperfine structure Physics Larmor precession Multidisciplinary 010405 organic chemistry Electron Spin Resonance Spectroscopy Resonance Statistical model ENDOR 0104 chemical sciences Biophysics and Computational Biology Protein Subunits Physical Sciences Density functional theory error model |
| Zdroj: | Proceedings of the National Academy of Sciences of the USA Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.2023615118 |
| Popis: | Significance Statistical modeling of experimental data is gaining increasing importance in biological science due to the availability of large datasets. Here we present a statistical analysis of electron–nuclear double resonance, a technique that delivers information on the angstrom to nanometer scale around paramagnetic centers in proteins. The described method allows for recognizing experimental artifacts and provides the most probable signal as well as its uncertainty. Application to representative high-field electron–nuclear double resonance spectra of a prototype tyrosyl radical in a protein, the β2 subunit of Escherichia coli ribonucleotide reductase, demonstrates that subtle information can be uncovered, such as a distribution of molecular orientations relevant for the biological function of this essential radical. Electron–nuclear double resonance (ENDOR) measures the hyperfine interaction of magnetic nuclei with paramagnetic centers and is hence a powerful tool for spectroscopic investigations extending from biophysics to material science. Progress in microwave technology and the recent availability of commercial electron paramagnetic resonance (EPR) spectrometers up to an electron Larmor frequency of 263 GHz now open the opportunity for a more quantitative spectral analysis. Using representative spectra of a prototype amino acid radical in a biologically relevant enzyme, the Y122• in Escherichia coli ribonucleotide reductase, we developed a statistical model for ENDOR data and conducted statistical inference on the spectra including uncertainty estimation and hypothesis testing. Our approach in conjunction with 1H/2H isotopic labeling of Y122• in the protein unambiguously established new unexpected spectral contributions. Density functional theory (DFT) calculations and ENDOR spectral simulations indicated that these features result from the beta-methylene hyperfine coupling and are caused by a distribution of molecular conformations, likely important for the biological function of this essential radical. The results demonstrate that model-based statistical analysis in combination with state-of-the-art spectroscopy accesses information hitherto beyond standard approaches. |
| Databáze: | OpenAIRE |
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