Characterization of an Oxygen-Evolving Photosystem II Complex from a Thermophilic Cyanobacterium Synechococcus Sp.

1984 ◽  
pp. 655-658
Author(s):  
G. H. Schatz ◽  
H. T. Witt
Keyword(s):  
Photosystem Ii ◽  
Thermophilic Cyanobacterium ◽  
Synechococcus Sp ◽  
Oxygen Evolving

Isolation and Partial Characterization of a Manganese and Chloride Binding Protein Present in Highly Purified Photosystem II Complexes of the Thermophilic Cyanobacterium Synechococcus sp.: The Protein Being Detected by Its L -Arginine Metabolizing Activity

1994 ◽  
Vol 49 (1-2) ◽  
pp. 95-107 ◽  
Author(s):  
Mathias Ruff ◽  
Elfriede K. Pistorius
Keyword(s):  
Photosystem Ii ◽  
Maximal Activity ◽  
Chloride Binding ◽  
Ps Ii ◽  
Thermophilic Cyanobacterium ◽  
Unknown Structure ◽  
Synechococcus Sp ◽  
Metabolizing Enzyme ◽  
Assay Conditions

Photosystem II complexes were solubilized with the detergent sulfobetaine 12 from thylakoid membranes of the thermophilic cyanobacterium Synechococcus sp. and purified by two sucrose gradient centrifugations and by chromatography on a Mono Q column. In such photosystem II complexes having a photosynthetic O2, evolving activity of 2938 μmol O2 evolved/mg chlorophyll x h, an ʟ-arginine metabolizing activity leading to ornithine and urea as major products, could be shown to be present. Besides ornithine and urea, a product (or products) of yet unknown structure is formed in addition - especially under aerobic conditions. This activity remained associated with photosystem II complexes even after substantial additional treatments to remove loosely bound proteins. On chlorophyll basis the maximal activity obtained under optimal assay conditions corresponded to 94 μmol ornithine formed/mg chlorophyll x h. This PS II associated, ʟ-arginine metabolizing enzyme was isolated (utilizing a manganese charged chelating Sepharose 6 B column) and partially characterized. It could be shown that this enzyme requires manganese and chloride for its ʟ-arginine metabolizing activity and that manganese becomes totally lost during purification indicating that manganese is bound to a fairly exposed site on the protein. Since it is rather unlikely that two different manganese and chloride binding proteins are present in such highly purified photosystem II complexes, the possibility of this protein being the water oxidizing enzyme will be discussed. Whether the manganese and chloride requiring ʟ-arginine metabolizing activity of this protein which provided a suitable assay for its isolation from photosystem II complexes, has any physiological significance, can not be answered at the present time.

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

Characterization of a resolved oxygen-evolving Photosystem II preparation from spinach thylakoids

1983 ◽  
Vol 724 (2) ◽  
pp. 201-211 ◽  
Author(s):  
Eric Lam ◽  
Barbara Baltimore ◽  
William Ortiz ◽  
Susan Chollar ◽  
Anastasios Melis ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Oxygen Evolving ◽  
Spinach Thylakoids
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