Biochimica et Biophysica Acta

No abstract text is available yet for this article.

No abstract text is available yet for this article.

No abstract text is available yet for this article.

No abstract text is available yet for this article.

No abstract text is available yet for this article.

Molecular weights of the purified light-harvesting complexes B800-850 and B875 from purple bacterium Rubrivivax gelatinosus were determined in detergent solutions by analytical centrifugation. The precise density measurement of the antenna solutions provided the values of the buoyant factor of both complexes. Phospholipid content was measured in both antennae. Sedimentation velocity and equilibrium centrifugation indicated that the B800-850 sample is monodisperse and composed from heptamers (α/β/3 Bacteriochlorophyll α 1...

Both short-term and long-term adaptations of cyanobacterial metabolism to light and dark were studied in Nostoc sp. Mac. Long-term adaptations were induced by growing cells in the presence of glucose under (a) 30 μE m-2 s-1 continuous white light, (b) under a 14/10 h light/dark cycle, or (c) complete darkness. Short-term regulation of enzyme activities by light was then studied in cells rendered osmotically fragile with lysozyme. Cells were briefly illuminated then enzyme activities were measured following rapid lysis in a hypotonic assay medium...

The whereabouts of the Ca2+ site in Photosystem II (PSII) was investigated by experiments in which Mn2+ was substituted for Ca2+ . When stoichiometric amounts of Mn2+ ions were added to Ca2+ -depleted PSII, the Mn2+ was not detected by EPR. The titration of Ca2+ back into Ca2+ -depleted/Mn2+ -containing PSII resulted in the simultaneous release of the Mn2+ and the loss of the two EPR signals which are characteristic of the Ca2+ -depleted enzyme (i.e., the stable, modified S2 multiline signal arising from the intrinsic Mn cluster and the split S3 signal from an organic radical interacting with the Mn cluster)...

The role of the acidic patches of spinach plastocyanin in the interaction with a soluble form of turnip cytochrome ƒ was studied by a combination of site-directed mutagenesis, NMR spectroscopy and kinetic analysis. The charge of the two 'eastern' patches, consisting of conserved acidic residues 42-45 and 59-61 respectively, was altered by incorporation of neutral or positively charged groups. Up to four negative charges were deleted in six different mutants and a further mutant, Q88E, provided an additional negative charge in the same region...

An EPR signal at g = 6.8 attributed to the cytochrome (Cyt) b-559 heme Fe(III) ligated by OH- (Fiege, R., Schrieber, U., Lubitz, W., Renger, G. and Shuvalov, V.A. (1995) FEBS Lett. 377, 325-329) was studied. This signal is observed in intact chloroplasts when oxidized by 10 mM 2,3-dicyano,5,6-dichloro-p-benzoquinone (DDQ), but not when 5 mM p-benzoquinone is added. Addition of KF (100 mM) or removal of Ca 21 for blocking the water-oxidizing complex considerably decreases the heme Fe(III)-OH- EPR signal. In contrast, DCMU does not decrease this signal and does not influence its photochemical changes at 140 K...