Photosystem II (PSII), which catalyzes photosynthetic water oxidation, is composed of more than 20 subunits, including membrane-intrinsic and -extrinsic proteins. The PSII extrinsic proteins shield the catalytic Mn4CaO5 cluster from the outside bulk solution and enhance binding of inorganic cofactors, such as Ca(2+) and Cl(-), in the oxygen-evolving center (OEC) of PSII. Among PSII extrinsic pr...

We have examined the assembly of the nuclear-encoded subunits of the oxygen-evolving complex (OEC) after their import into isolated intact chloroplasts. We showed that all three subunits examined (OE33, OE23, and OE17) partition between the thylakoid lumen and a site on the inner surface of the thylakoid membrane after import in a homologous system (e.g., pea or spinach subunits into pea or spi...

BACKGROUND Despite endometriosis is common estrogen dependent disease afflicting women in reproductive age, the pathogenesis has not been fully elucidated. Retinoic acid has various functions in cells as biologic modulator, and aberrant retinoid metabolism seems to be involved in the lesions of endometriosis. In order to evaluate the potential of all-trans retinoic acid (ATRA) for therapeutic t...

The oxygen-evolving complex (OEC) of photosystem II (PS II) consists of at least three extrinsic membrane-associated protein subunits, OE33, OE23, and OE17, with associated Mn2+, Ca2+, and Cl- ions. These subunits are bound to the lumen side of PS II core proteins embedded in the thylakoid membrane. Our experiments reveal that a significant fraction of each subunit is normally present in unasse...

Contusive spinal cord injury (SCI) results in a complex lesion that includes cellular and axonal loss, microglia and macrophage activation, and demyelination. These changes result in permanent neurological deficits in people with SCI and in high financial costs to society. Unlike the peripheral nervous system (PNS), in which axonal regeneration can occur, axonal regeneration in the central nerv...

Light-driven oxidation of water into dioxygen, catalysed by the oxygen-evolving complex (OEC) in photosystem II, is essential for life on Earth and provides the blueprint for devices for producing fuel from sunlight. Although the structure of the OEC is known at atomic level for its dark-stable state, the mechanism by which water is oxidized remains unsettled. Important mechanistic information ...

This paper reports computational studies of substrate water binding to the oxygen-evolving centre (OEC) of photosystem II (PSII), completely ligated by amino acid residues, water, hydroxide and chloride. The calculations are based on quantum mechanics/molecular mechanics hybrid models of the OEC of PSII, recently developed in conjunction with the X-ray crystal structure of PSII from the cyanoba...

Tanaka et al. (J. Am. Chem. Soc., 2017, 139, 1718) recently reported the three-dimensional (3D) structure of the oxygen evolving complex (OEC) of photosystem II (PSII) by X-ray diffraction (XRD) using extremely low X-ray doses of 0.03 and 0.12 MGy. They observed two different 3D structures of the CaMn4O5 cluster with different hydrogen-bonding interactions in the S1 state of OEC keeping the sur...

The second-shell ammonia binding sites near the OEC (oxygen-evolving complex) of PSII are characterized by combined Continuum Electrostatic/Monte Carlo (MCCE), QM/MM and DFT calculations and compared with new and earlier experimental measurements. MCCE shows ammonia has significant affinity at 6 positions but only two significantly influence the OEC. Although the pKa of ammonium ion is 9.25, it...

The olfactory ensheathing cell (OEC) has attracted much interest recently because of its potential for transplantation-based therapy of CNS disease. Rat OECs are able to remyelinate demyelinated axons and support regeneration of damaged axons. Although OECs can be grown readily from the rat, a macrosmatic species, it has been uncertain whether it would be similarly straightforward to obtain the...