ISSN:
1573-5079
Keywords:
Photosystem I
;
crystals of Photosystem I
;
electron microscopy
;
gel filtration HPLC
;
EPR
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract An active photosystem (PSI) complex was isolated from a phycobilisome-less mutant of the mesophilic cyanobacterium Synechococcus PCC 7002 by a mild procedure. Purification of PS I was achieved using a sucrose density gradient and an isoelectric focussing subsequent to the extraction of PSI from thylakoids with dodecyl-β-maltoside. Electron microscopy and gel filtration HPLC suggested that the isolated complex represents a trimeric form of PSI. The trimeric form was resistant to pH or detergent exchange. A ‘molecular weight’ of 690 kDa to 760 kDa has been determined for the complex by gel filtration HPLC in several detergents or mixtures of detergents. The PSI complex contains the polypeptides of the psaA, psaB, psaC, psaD, psaE, psaL gene products and two small polypeptides as determined by SDS-PAGE and N-terminal sequencing; its antenna size is 77±2 Chl a/P700. The full set of Fe-S clusters (FA, FB and FX) was observed by EPR-spectroscopy. A preliminary characterization of crystals obtained from this preparation was carried out using SDS-PAGE, optical and EPR spectroscopy.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00016559
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