title: Modeling light-driven proton pumps in artificial photosynthetic reaction centers.
abstract: We study a model of a light-induced proton pump in artificial reaction centers. The model contains a molecular triad with four electron states (i.e., one donor state, two photosensitive group states, and one acceptor state) as well as a molecular shuttle having one electron and one proton-binding sites. The shuttle diffuses between the sides of the membrane and translocates protons energetically uphill: from the negative side to the positive side of the membrane, harnessing for this purpose the energy of the electron-charge separation produced by light. Using the methods of quantum transport theory we calculate the range of light intensity and transmembrane potentials that maximize both the light-induced proton current and the energy transduction efficiency. We also study the effect of temperature on proton pumping. The light-induced proton pump in our model gives a quantum yield of proton translocation of about 55%. Thus, our results explain previous experiments on these artificial photosynthetic reaction centers.
authors.affiliation: Advanced Science Institute, The Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama 351-0198, Japan.
authors.forename: Pulak Kumar
authors.initials: PK
authors.lastname: Ghosh
authors.forename: Anatoly Yu
authors.initials: AY
authors.lastname: Smirnov
authors.forename: Franco
authors.initials: F
authors.lastname: Nori
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry* / Q000528:radiation effects*; D032701:Biomimetics; D008027:Light; D008956:Models, Chemical; D010788:Photosynthesis / Q000528:radiation effects; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000528:radiation effects; D017494:Proton Pumps / Q000737:chemistry* / Q000528:radiation effects; D011789:Quantum Theory; D013696:Temperature
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D017494:Proton Pumps