Light-harvesting proteins

As an example, a series of transient hole-bnming spectra obtained with a chirp-compensated continuum probe with a light-harvesting protein is shown in figure B2.1.7 [112]. As the probe delay increases, tire initially... 

Figure B2.1.7 Transient hole-burned speetra obtained at room temperature with a tetrapyrrole-eontaining light-harvesting protein subunit, the a subunit of C-phyeoeyanin. Top fluoreseenee and absorption speetra of the sample superimposed with die speetnuu of the 80 fs pump pulses used in the experiment, whieh were obtained from an amplified CPM dye laser operating at 620 mn. Bottom absorption-diflferenee speetra obtained at a series of probe time delays.

Figure B2.1.10 Stimulated photon-echo peak-shift (3PEPS) signals. Top pulse sequence and iuterpulse delays t and T. Bottom echo signals scaimed as a fiinction of delay t at tluee different population periods T, obtained with samples of a tetrapyrrole-containing light-harvesting protein subunit, the a subunit of C-phycocyanin.

Lithium dodecyl sulfate causes dramatic perturbations of the protein environment of the B800-850 light-harvesting protein of Rhodopseudomonas acido-... 

Membrane-bound proteins extend from the cytoplasmic membrane. Analysis by the method of Kyte and Doolittle 186> is quite useful for predicting the protein segments extending into the cytoplasmic membrane. The Kyte and Doolittle method, the so-called hydropathic index method, if it is coupled with the Chou-Fasman method, safely differentiates the protein segment which is located outside the membrane, from the helices within the membrane. The best examples are cytochrome P-450 187), cytochrome b5188), reaction centers 189,190) and light-harvesting protein comple-... 

Figure 23-30 Views of light-harvesting protein LHCII of green plants. (A) Side view indicating the approximate position in the lipid bilayer of the thylakoid membrane. Helices are labeled A-D. (B) Stereoscopic top view from the stromal side of the membrane. The structure, at 0.34 nm resolution, was determined by electron crystallography on highly ordered two-dimensional crystals. MolScript drawings from Kuhlbrandt et al.3W Courtesy of Werner Kiihlbrandt.

The thylakoid membranes contain the energy-transducing machinery light-harvesting proteins, reaction centers, electron-transport chains, and ATP synthase. They have nearly equal amounts of lipids and proteins. The lipid composition is highly distinctive about 40% of the total lipids are galactolipids and 4% are sulfolipids, whereas only 10% are... 

Table I. Summary of photosystem-l peripheral light-harvesting proteins fractionated from spinach and barley as designated In different nomenclatures, and names of their assigned genes and gene products...

Photosynthesis in purple bacteria commences with the excitation of P, the energy for such excitation being transferred directly from surrounding light harvesting proteins. The excited state P then decays in a charge... 

Carotenoids as Components of the Light-harvesting Proteins of Eukaryotic Algae... 

Effect of Light Intensity and Quality on the Petidinin-Containing Light-Harvesting Proteins. 90... 

Table 1. Comparison of various mature chromophyte light-harvesting protein sequences using the program Bestfit (Wisconsin Package, 1994). The sequences used are - Macrocystts, Apt et al., 1995 Phaeodactylum, Bhaya and Grossman 1993 Giraudyopsis, Passequet and Lichtle, 1995 Isochrysis LaRoche et al., 1994 Amphidinium, Hiller et al., 1995. Figures are % identity/ % similarity.

Fig. 9. Alignment of four chromophyte intrinsic light-harvesting proteins using the programme Pileup. girau Giraudyopsis (Passequet and Lichtle, 1995) mapyrWacTOcys//s(Aptetal., 1995) phatr/ /iae>/Hm(Bhaya and Grossman, 1993) acart/l/npfe (fjn m (Hiller et al., 1995). The approximate position of putative transmembrane helices are underlined. = identity with top sequence . a space.

An involvement of carotenoids in the thylakoid insertion of light-harvesting proteins has also been concluded from a pulse-chase measurement of the rate of protein insertion into membranes that have reduced amounts of carotenoids, due to norflurazon treatment (Dahlin and Timko, 1997). It should be kept in mind that carotenoids may also control other biosynthetic steps in the synthesis and assembly of light-harvesting complexes such as the import of the protein precursors into plastids (Dahlin, 1993 Dahlin and Franz6n, 1997). 

Zurdo J, Centeno MA, Odriozola JA, Fernandez-Cabrera C and Ramirez JM (1995) The structural role of the carotenoid in the bacterial light-harvesting protein 2 (LH2) of Rhodobacter capsulatus. A Fourier transform Raman spectroscopy and circular dichroism study. Photosynth Res 46 363-369... 

V. Resonance Raman of Carotenoid Molecules In Vivo Light-Harvesting Proteins.196... 

A. Light-Harvesting Proteins from Purple Bacteria.196... 

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