scholarly journals Molecular architecture of a light-harvesting antenna. In vitro assembly of the rod substructures of Synechococcus 6301 phycobilisomes.

1981 ◽  
Vol 256 (7) ◽  
pp. 3580-3592 ◽  
Author(s):  
D.J. Lundell ◽  
R.C. Williams ◽  
A.N. Glazer
Keyword(s):  
Light Harvesting ◽  
Molecular Architecture ◽  
In Vitro Assembly ◽  
Synechococcus 6301 ◽  
Light Harvesting Antenna

Acclimation of the Photosynthetic Apparatus to Photosystem I or Photosystem II Light: Evidence from Quantum Yield Measurements and Fluorescence Spectroscopy of Cyanobacterial Cells

1989 ◽  
Vol 44 (1-2) ◽  
pp. 109-118 ◽  
Author(s):  
Anastasios Melis ◽  
Conrad W. Mullineaux ◽  
John F. Allen
Keyword(s):  
Quantum Yield ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Oxygen Evolution ◽  
Photosystem I ◽  
Light Harvesting ◽  
Ps Ii ◽  
Ps I ◽  
Synechococcus 6301 ◽  
Light Harvesting Antenna

Abstract Cells of the cyanobacterium Synechococcus 6301 were grown under illumination whose spectral composition favoured absorption either by the phycobilisome (PBS) light-harvesting antenna of photosystem II (PS II) or by the chlorophyll (Chi) a light-harvesting antenna of photosystem I (PS I). Cells grown under PS I-light developed relatively high PS II/PS I and PBS/Chl ratios. Cells grown under PS II-light developed relatively low PS II/PS I and PBS/Chl ratios. Thus, the primary difference between cells in the two acclimation states appeared to be the relative concentration of PBS-PS II and PS I complexes in the thylakoid membrane. Measurements of the quantum yield of oxygen evolution suggested a higher efficiency of cellular photosynthesis upon the adjustment of photosystem stoichiometry to a specific light condition. The quantum yield of oxygen evolution was nevertheless lower under PBS than Chi excitation, suggesting quenching of excitation energy in the photochemical apparatus of PS II in Synechococcus 6301. This phenomenon was more pronounced in the PS II-light than in the PS I-light grown cells. Room temperature and 77 K fluorescence emission spectroscopy indicated that excess excitation energy in the PBS was not transferred to PS I, suggesting the operation of a non-radiative and non-photochemical decay of excitation energy at the PBS-PS II complex. This non-photochemical quenching was specific to conditions where excitation of PS II occurred in excess of its capacity for useful photochemistry.

The Bakerian Lecture, 1977: In vitro models for photosynthesis

1978 ◽  
Vol 362 (1710) ◽  
pp. 281-303 ◽  
Keyword(s):  
Light Harvesting ◽  
Living System ◽  
In Vitro Models ◽  
Concentration Quenching ◽  
Theoretical Studies ◽  
Interesting Part ◽  
Kinetic Investigations ◽  
Light Harvesting Antenna ◽  
And Storage

Attempts to construct, in vitro , systems which imitate parts of the photosynthetic process serve two purposes. First, they may confirm, or not confirm, structures and mechanisms proposed on the basis of analyses of the living system. Second, they may lead to a purely photochemical system for the capture and storage of solar energy. For the latter purpose, the most interesting part of the photosynthetic process is photosystem II, in which water is split by visible light into oxygen and a reduced material. The principal stages of the process are probably ( a ) light harvesting and trapping, ( b ) electron transfer from chlorophyll to a quinone, and ( c ) oxidation of water via an intermediate containing manganese. Each of these three processes has now been reproduced to some extent in vitro but the light harvesting antenna efficiencies are lowered by concentration quenching. Recent progress, including kinetic investigations in the picosecond region and theoretical studies of energy transfer in the antenna are described.

The Bakerian Lecture, 1977 - In vitro models for photosynthesis

1978 ◽  
Vol 202 (1149) ◽  
pp. 539-539
Keyword(s):  
Light Harvesting ◽  
Living System ◽  
In Vitro Models ◽  
Concentration Quenching ◽  
Theoretical Studies ◽  
Interesting Part ◽  
Kinetic Investigations ◽  
Light Harvesting Antenna ◽  
And Storage

Attempts to construct, in vitro , systems which imitate parts of the photosynthetic process serve two purposes. First, they may confirm, or not confirm, structures and mechanisms proposed on the basis of analyses of the living system. Second, they may lead to a purely photochemical system for the capture and storage of solar energy. For the latter purpose, the most interesting part of the photosynthetic process is photosystem II, in which water is split by visible light into oxygen and a reduced material. The principal stages of the process are probably ( a ) light harvesting and trapping, ( b ) electron transfer from chlorophyll to a quinone, and ( c ) oxidation of water via an intermediate containing manganese. Each of these three processes has now been reproduced to some extent in vitro but the light harvesting antenna efficiencies are lowered by concentration quenching. Recent progress, including kinetic investigations in the picosecond region and theoretical studies of energy transfer in the antenna are described.

In vitro assembly of 2-D crystals from partially purified EA1 protein secreted by Bacillus anthracis strain Delta Sterne-1

1994 ◽  
Vol 52 ◽  
pp. 276-277
Author(s):  
Mary Beth Downs ◽  
Wilson Ribot ◽  
Joseph W. Farchaus
Keyword(s):  
Cell Wall ◽  
Molecular Sieves ◽  
Cell Envelope ◽  
Single Species ◽  
Supporting Cell ◽  
Surface Layers ◽  
Rabbit Igg ◽  
In Vitro Assembly ◽  
Covalently Linked

Many bacteria possess surface layers (S-layers) that consist of a two-dimensional protein lattice external to the cell envelope. These S-layer arrays are usually composed of a single species of protein or glycoprotein and are not covalently linked to the underlying cell wall. When removed from the cell, S-layer proteins often reassemble into a lattice identical to that found on the cell, even without supporting cell wall fragments. S-layers exist at the interface between the cell and its environment and probably serve as molecular sieves that exclude destructive macromolecules while allowing passage of small nutrients and secreted proteins. Some S-layers are refractory to ingestion by macrophages and, generally, bacteria are more virulent when S-layers are present.When grown in rich medium under aerobic conditions, B. anthracis strain Delta Sterne-1 secretes large amounts of a proteinaceous extractable antigen 1 (EA1) into the growth medium. Immunocytochemistry with rabbit polyclonal anti-EAl antibody made against the secreted protein and gold-conjugated goat anti-rabbit IgG showed that EAI was localized at the cell surface (fig 1), which suggests its role as an S-layer protein.

Sign in / Sign up

Export Citation Format

Share Document