Great progress in the study of structure and dynamics of photosynthetic light-harvesting pigment−protein complexes has recently resulted in detailed understanding of the light-harvesting and light-...

Photosynthetic light-harvesting: Reconciling dynamics and structure of purple bacterial LH2 reveals function of photosynthetic unit

https://research.vu.nl/ws/files/2601041/PMC1302012.pdf

Absorption and CD spectroscopy and modeling of various LH2 complexes from purple bacteria

The existence of at least three low-energy chlorophyll a (Chl a ) antenna states is shown for photosystem I (PS I) of Synechococcus elongatus by the use of nonphotochemical hole burning (NPHB) spectroscopy. In addition to the previously reported states at 708 and 719 nm, it is demonstrated that there is a third state at 715 nm. The responsible Chl a molecules are referred to as C-708, C-715 and C-719. For both Synechococcus and Synechocystis , the lowest energy state is shown to be characterized by strong electron–phonon coupling (large Huang-Rhys factor S ), large permanent dipole moment change ( f · Δμ ), and large linear pressure shift rates attributable to electron exchange of dimeric Chl a . The lowest energy state of Synechocystis is at 714 nm. The properties of the 714 and 719 nm states are very similar, suggesting that their dimer structures are also similar. Although the other red antenna states of these cyanobacteria have smaller values for S , f · Δμ , and linear pressure shift rate, these are still larger than typically measured for monomeric antenna Chl a . Possible assignments of red absorption bands to particular chlorophyll dimers or trimer are discussed.

Red antenna states of photosystem I from cyanobacterium Synechococcus elongatus: a spectral hole burning study

Molecular mechanics calculations and exciton theory have been used to study pigment organization in chlorosomes of green bacteria. Single and double rod, multiple concentric rod, lamella, and Archimedean spiral macrostructures of bacteriochlorophyll c molecules were created and their spectral properties evaluated. The effects of length, width, diameter, and curvature of the macrostructures as well as orientations of monomeric transition dipole moment vectors on the spectral properties of the aggregates were studied. Calculated absorption, linear dichroism, and polarization dependent fluorescence-excitation spectra of the studied long macrostructures were practically identical, but circular dichroism spectra turned out to be very sensitive to geometry and monomeric transition dipole moment orientations of the aggregates. The simulations for long multiple rod and spiral-type macrostructures, observed in recent high-resolution electron microscopy images (Oostergetel et al., FEBS Lett 581:5435–5439, 2007) gave shapes of circular dichroism spectra observed experimentally for chlorosomes. It was shown that the ratio of total circular dichroism intensity to integrated absorption of the Qy transition is a good measure of degree of tubular structures in the chlorosomes. Calculations suggest that the broad Qy line width of chlorosomes of sulfur bacteria could be due to (1) different orientations of the transition moment vectors in multi-walled rod structures or (2) a variety of Bchl-aggregate structures in the chlorosomes.

Investigation on chlorosomal antenna geometries: tube, lamella and spiral-type self-aggregates

https://opus.lib.uts.edu.au/bitstream/10453/55795/1/BBA_V21ref.pdf

Challenges facing an understanding of the nature of low-energy excited states in photosynthesis.

Stark hole-burning spectroscopy at 1.8 K was used to determine the dipole moment changes fΔμ (f, the local field correction factor) for the B800 absorption band of the light harvesting 2 (LH2) complex of Rhodobacter sphaeroides, Rhodopseudomonas acidophila (strain 10050), and Rhodospirillum molischianum. Hole-burning values of fΔμ for the lowest energy exciton level (B870) associated with LH2's B850 band have recently been reported (Ratsep et al. Spectrochim. Acta, in press). Values for the lowest energy exciton level (B896) associated with the B875 band of the LH1 complex of Rb. sphaeroides (wild-type chromatophores and an LH1-only mutant) and the 825 nm band of the bacteriochlorophyll a (FMO) antenna complex of Chlorobium tepidum are also reported. For each band, fΔμ was determined for burn laser polarization parallel and perpendicular to the Stark field ES and several burn frequencies. The dependencies on laser polarization and burn frequency are typically quite weak. Importantly, fΔμ values for the ab...

Stark Hole-Burning Studies of Three Photosynthetic Complexes

High-pressure and stark hole-burning studies of chlorosome antennas from Chlorobium tepidum.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

† H.-M. Wu

Author Tools

Chat about Author

Papers

Stark Hole-Burning Studies of Three Photosynthetic Complexes

High-pressure and stark hole-burning studies of chlorosome antennas from Chlorobium tepidum.