Quenching of chlorophyll fluorescence by quinones

Abstract

Quinones caused quenching of Chl a fluorescence in native and model systems. Menadione quenched twofold the fluorescence of Chl a and BChl a in pea chloroplasts, chromatophores of purple bacteria, and liposomes at concentrations of 50‐80 μM. To obtain twofold quenching in Triton X‐100 micelles and in ethanol, the addition of 1.3 mM and 11 mM menadione was required, respectively. A proportional decrease in the lifetime and yield of Chl a fluorescence in chloroplasts, observed as the menadione concentration increased, is indicative of the efficient excitation energy transfer from bulk Chl to menadione. The decrease in the lifetime and yield of fluorescence was close to proportional in liposomes, but not in detergent micelles. The insensitivity of the menadione quenching effect to DCMU in chloroplasts, and similarity of its action in chloroplasts and liposomes indicate that menadione in chloroplasts interacts with antenna Chl, i. e., nonphotochemical quenching of fluorescence occurs.

Diblock Copolymer Micelles and Supported Films with Noncovalently Incorporated Chromophores: A Modular Platform for Efficient Energy Transfer

“…33 In contrast, the polymer-driven assembly process allows modularity, with the potential for incorporation of practically any desired hydrophobic or amphiphilic cofactor into the same basic architecture. Future applications of polymer-based LH nanocomposites could also allow the non-covalent incorporation of biological electron carriers, 34 or carbon nanomaterials such as fullerenes 35,36 or carbon nanotubes 37 , allowing electron-active assemblies and new functional devices. Photosynthetic membranes are highly responsive, often changing the composition and organization of LH pigment-protein components in response external stimuli, such as light intensity [38][39][40] , oxygen tension, 40 and genetic mutation.…”

“…33 In contrast, the polymer-driven assembly process allows modularity, with the potential for incorporation of practically any desired hydrophobic or amphiphilic cofactor into the same basic architecture. Future applications of polymer-based LH nanocomposites could also allow the noncovalent incorporation of biological electron carriers, 34 or carbon nanomaterials such as fullerenes 35,36 or carbon nanotubes, 37 and allow electron-active assemblies and new functional devices.…”

Photoinduced Electron Transfer between Chlorophyllaand Gold Nanoparticles

“…In this regard, Chla-quinones, as donor-acceptor systems, have been widely studied as simple photosynthetic models. [15][16][17][18][19][20][21][22][23] A reduced fluorescence quantum yield or lifetime, or a decreased triplet quantum yield of the donor, suggests that the electron transfer occurs from an excited donor. Further, the detection of cation radical of the donor and anion radical of the acceptor provides additional proof of the electron-transfer process.…”

“…Of particular interest has been the study of donor−acceptor systems containing Chl a that can mimic the photoinduced electron-transfer process of natural photosynthesis. In this regard, Chl a -quinones, as donor−acceptor systems, have been widely studied as simple photosynthetic models. − A reduced fluorescence quantum yield or lifetime, or a decreased triplet quantum yield of the donor, suggests that the electron transfer occurs from an excited donor. Further, the detection of cation radical of the donor and anion radical of the acceptor provides additional proof of the electron-transfer process.…”

Energy problems in life evolution

“…They deactivate long lived triplet chlorophyll (bacteriochloro phyll) and thus prevent its interaction with 3 O 2 , leading to formation of 1 O 2 *. There is another form of non photochemical quenching: quinones quench photoexcited chlorophyll (bacteri ochlorophyll) in natural and artificial systems [23,24]. Under intense illumination, excessive energy of excited chlorophyll is dissipated as heat; this non photochemical deactivation of excite ments involves special carotenoids, xanthophylls [22].…”