| Autor: |
Nishikawa G; Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan., Saito K; Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.; Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguru-ku, Tokyo 153-8904, Japan., Ishikita H; Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.; Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguru-ku, Tokyo 153-8904, Japan. |
| Abstrakt: |
Quinone analogue molecules, functioning as herbicides, bind to the secondary quinone site, Q B , in type-II photosynthetic reaction centers, including those from purple bacteria (PbRC). Here, we investigated the impact of herbicide binding on electron transfer branches, using herbicide-bound PbRC crystal structures and employing the linear Poisson-Boltzmann equation. In contrast to urea and phenolic herbicides [Fufezan, C. Biochemistry 2005, 44, 12780-12789], binding of atrazine and triazine did not cause significant changes in the redox-potential ( E m ) values of the primary quinone (Q A ) in these crystal structures. However, a slight E m difference at the bacteriopheophytin in the electron transfer inactive branch (H M ) was observed between the S (-)- and R (+)-triazine-bound PbRC structures. This discrepancy is linked to variations in the protonation pattern of the tightly coupled Glu-L212 and Glu-H177 pairs, crucial components of the proton uptake pathway in native PbRC. These findings suggest the existence of a Q B -mediated link between the electron transfer inactive H M and the proton uptake pathway in PbRCs. |
