THE METAL CENTERS OF THE PHOTOSYNTHETIC OXYGEN-EVOLVING COMPLEX

XAS of Mn in the Photosynthetic Oxygen, Evolving Complex

Nearly all of the dioxygen which animals and aerobic bacteria use during respiration originates from the photosynthetic oxygen evolving complex (OEC) which is found in the chloroplast thylakoid membranes of higher plants and algae. Four specifically bound Mn are required for OEC activity [l]. These manganese do not exhibit the six line epr spectrum which is characteristic of Mn(IIj in solution,...

Architecture of the photosynthetic oxygen-evolving center.

Photosynthesis uses light energy to drive the oxidation of water at an oxygen-evolving catalytic site within photosystem II (PSII). We report the structure of PSII of the cyanobacterium Thermosynechococcus elongatus at 3.5 angstrom resolution. We have assigned most of the amino acid residues of this 650-kilodalton dimeric multisubunit complex and refined the structure to reveal its molecular ar...

Glycinebetaine stabilizes the association of extrinsic proteins with the photosynthetic oxygen-evolving complex.

The photosynthetic oxygen-evolving activity of the photosystem 2 complex, prepared from spinach, was labile when the complex was exposed to high-salt conditions under which the extrinsic proteins were dissociated from the complex. Glycinebetaine prevented the dissociation of the 18-kDa and the 23-kDa extrinsic proteins from the photosystem 2 complex in the presence of 1 M NaCl. It also prevente...

Structural Proposals for the Manganese Centers of the Oxygen Evolving Complex: an Inorganic Chemist's Perspective*

This contribution provides an analysis of the basic coordination tendencies of manganese with specific emphasis on the biological chemistry of this element. The review is broken into four parts. First, a discussion of the basic coordination chemistry o f manganese is mononuclear and multinuclear environments is prescnted. Second, the biophysical data essential to the development of models for t...

Function of Extrinsic Proteins in Stabilization of the Photosynthetic Oxygen-Evolving Complex