Light harvesting particles

Antenna pigment proteins assemble into multimeric light-harvesting particles... 

DETronrud, MF Schmid and BW Mathews (1986) Structure and x-ray amino acid sequence of a bacteriochlo-rophyll a protein from Prosthecochloris aestuarii refined at 1.9 resolution. J Mol Biol 188 443-454 T Katoh, M MImuro and S Takalchl (1989) Light-harvesting particles Isolated from a brown alga, DIctyota dichotoma. A supramolecular assembly of fucoxanthin-chlorophyll-protein complexes. Biochim Biophys Acta 976 233-240... 

Fig 6. Absorption and second-derivative spectra of intact fucoxanthin-chlorophyll- a/c protein assembly (FCPA) at room temperature (A, top) and 77 K (A, bottom). Absorption spectra of intact and Triton-treated FCPA (B, top) and their difference spectrum between the two (B, bottom). Figure source Katoh, Mimuro and Takaichi (1989) Light-harvesting particles isolated from a brown alga, Dictyota dichotoma. A supramolecular assembly of fucoxanthin-chlorophyll-protein complexes. Biochim BiophysActa 968 236,237. 

T Katoh, M Mimuro and S Takaichi (1989) Light-harvesting particles isolated from a brown alga, Dictyota dichotoma. A supramolecular assembly of fucoxanthin-chlorophyll-protein complexes. Biochim Biophys Acta 976 233-240... 

Fig. 5.19 (a) Linking CdSe quantum dots to Ti02 particle with bifunctional surface modifier (b) light harvesting assembly composed of T102 film functionahzed with CdSe Q-dots on optically transparent electrode (OTE). [Adapted (in gray scale) from [348]]... 

Polymers interpenetration of polymer chains, phase separation, compatibility between polymers, interdiffusion of latex particles, interface thickness in blends of polymers, light-harvesting polymers, etc. 

Particularly promising is the development of nanoporous ceramic semiconductor membranes [692-695], They not only possess all of the advantages of ceramic materials, but they may also be efficient light harvesters having large surface areas which could provide sites for sensitizers [108, 711-714]. Indeed, FeS2 particles, deposited into (and onto) a porous Ti02 electrode, sensitized photoelectron conversion well (Fig. 118) [714]. 

In contrast to LHCI, the light-harvesting chlorophyll a/b-antennae complex of photosystem II (LHCII) is the major component of the particles on the complementary protoplasmic fracture face of appressed membranes (PFs) (Simpson, 1979, Olive et al., 1979), and does not appear to be a significant component of the reaction centre EFs particles, although this is disputed. The LHCII in PFs particles is, nevertheless, in contact with the reaction centre particles and may provide a pathway for excitation energy transfer between several photosystem II reaction centres. 

In all green bacteria the main antenna system is organized in small ovoid particles, the so-called chlorosomes, located adjacent to the cell membrane. The BChl c and d pigments are associated with this accessory light-harvesting system. 

Note that LHCll is a separate light-harvesting complex, which supplements the inner antennae (CP29, CP26, CP24 and CP22) associated with the PS-II complex. The presence of this separate LHC II complex has been confirmed by the results of freeze-fracture experiments obtained with thylakoid membranes of both wild-type and mutant plants. The PS-11 inner antenna complex and the LHC-II complex appear as distinctly different classes of membrane particles. On the other hand, the LHC-I proteins associated with the PS-1 complex appear to be complexed to the PS-1 reaction center, much as the inner antennae of PS II are complexed to the PS-II reaction center. 

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