functional model for O-O bond formation by the O2-evolving complex in photosystem II

• Published in: Science (American Association for the Advancement of Science) Vol. 283; no. 5407; pp. 1524 - 1527
• Main Authors: Limburg, J, Vrettos, J.S, Liable-Sands, L.M, Rheingold, A.L, Crabtree, R.H, Brudvig, G.W
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 05.03.1999; The American Association for the Advancement of Science
• Subjects: Biological and medical sciences; Catalysis; Chemical bonds; Dimerization; Electron Spin Resonance Spectroscopy; Fundamental and applied biological sciences. Psychology; Inhalants; Ligands; manganese; Manganese - chemistry; Manganese - metabolism; Manganese Compounds - chemistry; Metabolism; Models, Chemical; Organic Chemistry; Oxidation; Oxidation-Reduction; Oxides - chemistry; Oxygen; Oxygen - chemistry; Oxygen - metabolism; oxygen formation; Oxygen Isotopes; Photosynthesis; Photosynthesis, respiration. Anabolism, catabolism; Photosynthetic Reaction Center Complex Proteins - metabolism; photosystem II; Photosystem II Protein Complex; Plant physiology and development; Sodium Hypochlorite - chemistry; structural model complexes; Water; Water - chemistry; Water - metabolism; Photosystem 2; Oxygen; Enzymatic activity; Ultraviolet irradiation; Manganese II Complexes; Manganese III Complexes; Photosynthesis
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.283.5407.1524

The formation of molecular oxygen from water in photosynthesis is catalyzed by photosystem II at an active site containing four manganese ions that are arranged in di-mu-oxo dimanganese units (where mu is a bridging mode). The complex [H2O(terpy)Mn(O)2Mn(terpy)OH2](NO3)3 (terpy is 2,2':6',2"-terpyri-dine), which was synthesized and structurally characterized, contains a di-mu-oxo manganese dimer and catalyzes the conversion of sodium hypochlorite to molecular oxygen. Oxygen-18 isotope labeling showed that water is the source of the oxygen atoms in the molecular oxygen evolved, and so this system is a functional model for photosynthetic water oxidation.