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Identification of the Deprotonated Pyrrole Nitrogen of the Bilin-Based Photoreceptor by Raman Spectroscopy with an Advanced Computational Analysis

発表形態:
原著論文
主要業績:
単著・共著:
発表年月:
2019年04月
DOI:
10.1021/acs.jpcb.9b00965
会議属性:
査読:
リンク情報:

日本語フィールド

著者:
Osoegawa, Shinsuke; Miyoshi, Risako; Watanabe, Kouhei; Hirose, Yuu; Fujisawa, Tomotsumi; Ikeuchi, Masahiko; Unno, Masashi
題名:
Identification of the Deprotonated Pyrrole Nitrogen of the Bilin-Based Photoreceptor by Raman Spectroscopy with an Advanced Computational Analysis
発表情報:
Journal of Physical Chemistry B 巻: 123 号: 15 ページ: 3242 - 3247
キーワード:
概要:
Copyright © 2019 American Chemical Society. Phytochrome and cyanobacteriochrome utilize a linear methine-bridged tetrapyrrole (bilin) to control numerous biological processes. They show a reversible photoconversion between two spectrally distinct states. This photocycle is initiated by a C=C double-bond photoisomerization of the bilin followed by its thermal relaxations with transient and/or stationary changes in the protonation state of the pyrrole moiety. However, it has never been identified which of the four pyrrole nitrogen atoms is deprotonated. Here, we report a resonance Raman spectroscopic study on cyanobacteriochrome RcaE, which has been proposed to contain a deprotonated bilin for its green-absorbing 15Z state. The observed Raman spectra were well reproduced by a simulated structure whose bilin B ring is deprotonated, with the aid of molecular dynamics and quantum mechanics/molecular mechanics calculations. The results revealed that the deprotonation of B and C rings has the distinct effect on the overall bilin structure, which will be relevant to the color tuning and photoconversion mechanisms of the phytochrome superfamily. Furthermore, this study documents the ability of vibrational spectroscopy combined with the advanced spectral analysis to visualize a proton of a cofactor molecule embedded in a protein moiety.
抄録:

英語フィールド

Author:
Osoegawa, Shinsuke; Miyoshi, Risako; Watanabe, Kouhei; Hirose, Yuu; Fujisawa, Tomotsumi; Ikeuchi, Masahiko; Unno, Masashi
Title:
Identification of the Deprotonated Pyrrole Nitrogen of the Bilin-Based Photoreceptor by Raman Spectroscopy with an Advanced Computational Analysis
Announcement information:
Journal of Physical Chemistry B Vol: 123 Issue: 15 Page: 3242 - 3247
An abstract:
Copyright © 2019 American Chemical Society. Phytochrome and cyanobacteriochrome utilize a linear methine-bridged tetrapyrrole (bilin) to control numerous biological processes. They show a reversible photoconversion between two spectrally distinct states. This photocycle is initiated by a C=C double-bond photoisomerization of the bilin followed by its thermal relaxations with transient and/or stationary changes in the protonation state of the pyrrole moiety. However, it has never been identified which of the four pyrrole nitrogen atoms is deprotonated. Here, we report a resonance Raman spectroscopic study on cyanobacteriochrome RcaE, which has been proposed to contain a deprotonated bilin for its green-absorbing 15Z state. The observed Raman spectra were well reproduced by a simulated structure whose bilin B ring is deprotonated, with the aid of molecular dynamics and quantum mechanics/molecular mechanics calculations. The results revealed that the deprotonation of B and C rings has the distinct effect on the overall bilin structure, which will be relevant to the color tuning and photoconversion mechanisms of the phytochrome superfamily. Furthermore, this study documents the ability of vibrational spectroscopy combined with the advanced spectral analysis to visualize a proton of a cofactor molecule embedded in a protein moiety.


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