Tracing the Pathways of Waters and Protons in Photosystem II and Cytochrome c Oxidase

Inorganics

Yingying Zhang¹  Divya Kaur¹  Junjun Mao¹  MarilynR. Gunner¹  Manoj Mandal¹  Umesh Khaniya¹  Xiuhong Cai¹ 

[1] Department of Physics, City College of New York, New York, NY 10031, USA;

关键词: proton pumping;    network analysis;    proton affinity;    proton coupled electron transfer;   

DOI  :  10.3390/inorganics7020014

来源: DOAJ

【 摘 要 】

Photosystem II (PSII) uses water as the terminal electron donor, producing oxygen in the Mn₄CaO₅ oxygen evolving complex (OEC), while cytochrome c oxidase (CcO) reduces O₂ to water in its heme⁻Cu binuclear center (BNC). Each protein is oriented in the membrane to add to the proton gradient. The OEC, which releases protons, is located near the P-side (positive, at low-pH) of the membrane. In contrast, the BNC is in the middle of CcO, so the protons needed for O₂ reduction must be transferred from the N-side (negative, at high pH). In addition, CcO pumps protons from N- to P-side, coupled to the O₂ reduction chemistry, to store additional energy. Thus, proton transfers are directly coupled to the OEC and BNC redox chemistry, as well as needed for CcO proton pumping. The simulations that study the changes in proton affinity of the redox active sites and the surrounding protein at different states of the reaction cycle, as well as the changes in hydration that modulate proton transfer paths, are described.

【 授权许可】

Unknown