An EPR study of Signal II in oriented photosystem II membranes

Specific association of photosystem II and light-harvesting complex II in partially solubilized photosystem II membranes.

In this study, we report the structural characterization of photosystem II complexes obtained from partially solubilized photosystem II membranes. Direct observation by electron microscopy, within a few minutes after a mild disruption of the membranes with the detergent n-dodecyl-alpha,D-maltoside, revealed the presence of several large supramolecular complexes. Images of these complexes were s...

Supramolecular organization of photosystem II and its light-harvesting antenna in partially solubilized photosystem II membranes.

We present an extended analysis of the organization of green plant photosystem II and its associated light-harvesting antenna using electron microscopy and image analysis. The analysis is based on a large dataset of 16 600 projections of negatively stained PSII-LHCII supercomplexes and megacomplexes prepared by means of three different pretreatments. In addition to our previous work on this sys...

The S0 State of the Oxygen-Evolving Complex in Photosystem II Is Paramagnetic: Detection of an EPR Multiline Signal.

Copper(II) inhibition of electron transfer through photosystem II studied by EPR spectroscopy.

EPR spectroscopy was applied to investigate the inhibition of electron transport in photosystem II by Cu2+ ions. Our results show that Cu2+ has inhibitory effects on both the donor and the acceptor side of photosystem II. In the presence of Cu2+, neither EPR signal IIvery fast nor signal IIfast, which both reflect oxidation of tyrosinez, could be induced by illumination. This shows that Cu2+ in...

Cation-induced, inhibitor-resistant photosystem II reactions in cyanobacterial membranes.

Sumnary: Ferricyanide-supported oxygen evolution in sonic vesicles from the cyanobacterium Spirulina platensis is only partially sensitive to inhibition by 2,5dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), and addition of cations to inhibited membranes The order of cation effectiveness (M3 s imulates +> M 3 the rate of oxygen evolution. > M+) suggests that this stimulation is due at least...