| Autor: |
Fujisawa T; Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan., Tanaka N; Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan., Tamogami J; College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan., Unno M; Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan. |
| Abstrakt: |
Sensory rhodopsin II (SRII) is a prototype photosensor that binds the retinal Schiff base chromophore. Upon photoabsorption, SRII is transformed into the signaling state, where two long-lived photointermediates are known to contribute. One is the M intermediate containing the deprotonated 13- cis chromophore, and the other is the O intermediate that is believed to have the protonated all- trans chromophore. The chromophore in the O intermediate is also thought to have the atypical 15- syn (C═N cis ) configuration about the Schiff base moiety. In this communication, we study SRII from Natronomonas pharaonis ( Np SRII) using Raman spectroscopy and find that the retinal chromophore configuration in the O intermediate is the 13- cis , 15- anti (C═N trans ), contrary to the conventional notion. This result points out the revision of the chromophore structural changes underlying the long-lived signaling state of SRII. |
