Department of Chemistry, Umeå University, Linnaeus Väg 6 (KBC huset), 90187 Umeå, Sweden.
Chemistry. 2011 May 2;17(19):5415-23. doi: 10.1002/chem.201002548. Epub 2011 Apr 4.
Oxygen evolution catalysed by calcium manganese and manganese-only oxides was studied in (18)O-enriched water. Using membrane-inlet mass spectrometry, we monitored the formation of the different O(2) isotopologues (16)O(2), (16)O(18)O and (18)O(2) in such reactions simultaneously with good time resolution. From the analysis of the data, we conclude that entirely different pathways of dioxygen formation catalysis exist for reactions involving hydrogen peroxide (H(2)O(2)), hydrogen persulfate (HSO(5)(-)) or single-electron oxidants such as Ce(IV) and Ru(III) (bipy)(3) . Like the studied oxide catalysts, the active sites of manganese catalase and the oxygen-evolving complex (OEC) of photosystem II (PSII) consist of μ-oxido manganese or μ-oxido calcium manganese sites. The studied processes show very similar (18)O-labelling behaviour to the natural enzymes and are therefore interesting model systems for in vivo oxygen formation by manganese metalloenzymes such as PSII.
用膜进样质谱法，我们在这些反应中同时以良好的时间分辨率监测不同 O(2) 同位素（16)O(2)、(16)O(18)O 和 (18)O(2) 的形成。从数据分析中，我们得出结论，对于涉及过氧化氢 (H(2)O(2))、过硫酸氢盐 (HSO(5)(-)) 或单电子氧化剂（如 Ce(IV) 和 Ru(III)(bipy)(3)）的反应，存在完全不同的氧气形成催化途径。像研究的氧化物催化剂一样，锰过氧化物酶和光合作用系统 II (PSII)的氧气释放复合物 (OEC)的活性位点由 μ-氧代锰或 μ-氧代钙锰位点组成。所研究的过程表现出与天然酶非常相似的 (18)O 标记行为，因此是锰金属酶（如 PSII）体内氧气形成的有趣模型系统。
