Preparation of Active Fractions Enriched in Photosystem I and Photosystem II from the Thermophilic Blue-Green Alga Phormidium laminosum

1978 ◽  
Vol 6 (5) ◽  
pp. 1040-1041 ◽  
Author(s):  
ALISON C. STEWART ◽  
DEREK S. BENDALL
Keyword(s):  
Photosystem Ii ◽  
Green Alga ◽  
Photosystem I ◽  
Blue Green Alga ◽  
Phormidium Laminosum

scholarly journals Properties of oxygen-evolving photosystem-II particles from Phormidium laminosum, a thermophilic blue-green alga

1981 ◽  
Vol 194 (3) ◽  
pp. 877-887 ◽  
Author(s):  
A C Stewart ◽  
D S Bendall
Keyword(s):  
Photosystem Ii ◽  
Chlorophyll A ◽  
Green Alga ◽  
Fluorescence Emission ◽  
O2 Evolution ◽  
Fluorescence Emission Spectrum ◽  
Blue Green Alga ◽  
Photosynthetic Unit ◽  
Phormidium Laminosum ◽  
Photosystem Ii Particles

1. O2-evolving Photosystem-II particles from the thermophilic blue–green alga Phormidium laminosum contained 1 mol of Mn/13–17 mol of chlorophyll a compared with 1 mol of Mn/65–75 mol of chlorophyll a in unfractionated membranes. 2. At least two-thirds of the Mn in the Photosystem-II particles was removed by mild heating and by treatment with Tris or EDTA, with concomitant loss of O2 evolution. However, irreversible inactivation was also caused by washing in buffers without MgCl2, and this inactivation was not accompanied by a corresponding loss of Mn. 3. Bivalent cations (Mg2+ or Ca2+), Cl- or Br- ions and at least 20% (v/v) glycerol were required for maximum stability of O2 evolution. 4. The Photosystem-II particles were enriched in high-potential cytochrome b-559 (1 mol of cytochrome/50–60 mol of chlorophyll a) and in component C-550, and had a photosynthetic-unit size of 40–70 molecules of chlorophyll a. 5. The absorption spectrum at 77 K showed a preponderance of shorter-wavelength forms of chlorophyll a in the Photosystem-II particles, and in the fluorescence emission spectrum at 77 K there were major chlorophyll fluorescence bands at 684 nm and 695 nm, with almost no fluorescence in the far-red region. 6. Analysis of the lipid and protein contents showed that the Photosystem-II particles were not chemically pure (for example, all of the membrane-bound cytochromes and cytochrome c-549 were present), but their high O2-evolution activity and good optical properties make them useful for functional studies on Photosystem-II and O2 evolution.

scholarly journals Mössbauer spectra of photosystem-I-reaction centres from the blue-green alga Chlorogloea fritschii

1979 ◽  
Vol 182 (3) ◽  
pp. 861-865 ◽  
Author(s):  
E H Evans ◽  
J D Rush ◽  
C E Johnson ◽  
M C W Evans
Keyword(s):  
Green Alga ◽  
Photosystem I ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
Chemical Reduction ◽  
Blue Green Alga ◽  
Mossbauer Spectra ◽  
Maximum Reduction ◽  
Reaction Centres ◽  
Reduction Of Iron

Substantial amounts of iron have been shown by Mössbauer spectroscopy to be present in Photosystem-I preparations from the blue-green alga Chlorogloeta fritschii. Changes in the spectra on chemical reduction provide evidence that some of this iron is very similar to that found in the 4Fe-4S centres of ferredoxins. Such reduced samples also show e.p.r. signals consistent with maximum reduction of iron-sulphur centres A and B of Photosystem I. An unchanged component in the spectra indicates, assuming all centres A and B are reduced, the presence of another iron-containing species.

scholarly journals Chlorophyll triplet states associated with Photosystem I and Photosystem II in thylakoids of the green alga Chlamydomonas reinhardtii

2007 ◽  
Vol 1767 (1) ◽  
pp. 88-105 ◽  
Author(s):  
Stefano Santabarbara ◽  
Giancarlo Agostini ◽  
Anna Paola Casazza ◽  
Christopher D. Syme ◽  
P. Heathcote ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Chlamydomonas Reinhardtii ◽  
Green Alga ◽  
Photosystem I ◽  
Triplet States

scholarly journals Photosynthetic electron transport in a cell-free preparation from the thermophilic blue-green alga Phormidium laminosum

1980 ◽  
Vol 188 (2) ◽  
pp. 351-361 ◽  
Author(s):  
A C Stewart ◽  
D S Bendall
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Green Alga ◽  
Photosynthetic Electron Transport ◽  
High Potential ◽  
O2 Evolution ◽  
Blue Green Alga ◽  
Phormidium Laminosum ◽  
A Cell ◽  
Membrane Bound

1. A cell-free preparation of membrane fragments was prepared from the thermophilic blue-green alga Phormidium laminosum by lysozyme treatment of the cells followed by osmotic shock to lyse the spheroplasts. The membrane fragments showed high rates of photosynthetic electron transport and O2 evolution (180-250 mumol of O2/h per mg of chlorophyll a with 2,6-dimethyl-1,4-benzoquinone as electron acceptor). O2-evolution activity was stable provided that cations (e.g. 10mM-Mg2+ or 100mM-Na+) or glycerol (25%, v/v) were present in the suspending medium. 2. The components of the electron-transport chain in P. laminosum were similar to those of other blue-green algae: the cells contained Pigment P700, plastocyanin, soluble high-potential cytochrome c-553, soluble low-potential cytochrome c-54 and membrane-bound cytochromes f, b-563 and b-559 (both low- and high-potential forms). The amounts and midpoint potentials of the membrane-bound cytochromes were similar to those in higher-plant chloroplasts. 3. Although O2 evolution in P. laminosum spheroplasts was resistant to high temperatures, thermal stability was not retained in the cell-free preparation. However, in contrast with higher plants, O2 evolution in P. laminosum membrane fragments was remarkably resistant to the non-ionic detergent Triton X-100.

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