Synthetic model compounds have been targeted to benchmark and better understand the electronic structure, geometry, spectroscopy, and reactivity of the oxygen-evolving complex (OEC) of photosystem II, a low-symmetry Mn4CaOn cluster. Herein, low-symmetry Mn(IV)3GdO4 and Mn(IV)3CaO4 cubanes are synthesized in a rational, stepwise fashion through desymmetrization by ligand substitution, causing si...

The oxygen-evolving complex (OEC) of photosystem II is the only natural system that can form O2 from water and sunlight and it consists of a Mn4Ca cluster. In a series of publications, Siegbahn has developed a model of the OEC with the quantum mechanical (QM) cluster approach that is compatible with available crystal structures, able to form O2 with a reasonable energetic barrier, and has a sig...

The oxygen in the atmosphere is derived from light-driven oxidation of water at a catalytic centre contained within a multi-subunit enzyme known as photosystem II (PSII). PSII is located in the photosynthetic membranes of plants, algae and cyanobacteria and its oxygen-evolving centre (OEC) consists of four manganese ions and a calcium ion surrounded by a highly conserved protein environment. Re...

We present an algorithmic framework for producing Delaunay triangulations of manifolds. The input to the algorithm is a set of sample points together with coordinate patches indexed by those points. The transition functions between nearby coordinate patches are required to be bi-Lipschitz with a constant close to 1. The primary novelty of the framework is that it can accommodate abstract manifo...

This paper presents grey structure activity relationship analysis for phenolic acid phenethyl esters from the bioactivity on oral cancer SAS, OEC-M1 and human breast cancer MCF-7. First of all, 14 compounds of phenolic acid phenethyl esters are synthesized, while the bioactivity (cytotoxicity) on the cancer cells SAS, OEC-M1, MCF-7 is tested. Next, the relationship weighting of functional group...

Redox-inactive metal ions play crucial roles in tuning the reactivity of oxygen-containing metal complexes and metalloenzymes such as the oxygen-evolving complex (OEC) in photosystem II (PSII) and its small-molecule mimics. In PSII, a Ca ion is part of the tetrameric Mn cluster, Mn4CaO5, and is integral to the water oxidation catalysis and evolution of oxygen by the OEC. Several different funct...

Photosystem II (PSII) uses light energy to split water into protons, electrons and O2. In this reaction, nature has solved the difficult chemical problem of efficient four-electron oxidation of water to yield O2 without significant amounts of reactive intermediate species such as superoxide, hydrogen peroxide and hydroxyl radicals. In order to use nature's solution for the design of artificial ...

Oxygenic photosynthesis, which provides the biosphere with most of its chemical energy, uses water as its source of electrons. Water is photochemically oxidized by the protein complex photosystem II (PSII), which is found, along with other proteins of the photosynthetic light reactions, in the thylakoid membranes of cyanobacteria and of green plant chloroplasts. Water splitting is catalyzed by ...

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...