Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India.
Chemistry. 2017 Aug 1;23(43):10270-10275. doi: 10.1002/chem.201702321. Epub 2017 Jul 7.
MauG is a diheme enzyme that utilizes two covalently bound c-type heme centers. We report here step-wise oxidations of a synthetic analogue of MauG in which two heme centers are bridged covalently through a flexible linker containing a pyrrole moiety. One- and two-electron oxidations produce monocation radical and dication diradical intermediates, respectively, which, being highly reactive, undergo spontaneous intramolecular rearrangement involving the pyrrole bridge itself to form indolizinium-fused chlorin-porphyrin and spiro-porphyrinato heterodimers. Unlike in MauG, where the two oxidizing equivalents produce the bis-Fe redox state, the synthetic analogue of the same, however, stabilizes two ferric hemes, each coupled with a porphyrin π-cation radical. The present study highlights the possible role played by the bridge in the electronic communication.
MauG 是一种二血红素酶，利用两个共价结合的 c 型血红素中心。我们在此报告了 MauG 合成类似物的逐步氧化，其中两个血红素中心通过含有吡咯部分的柔性连接体共价桥接。一电子和两电子氧化分别产生单阳离子自由基和二阳离子二自由基中间体，它们具有很高的反应性，会自发地进行涉及吡咯桥本身的分子内重排，形成吲哚嗪并合的氯代叶绿素-卟啉和螺-卟啉并杂二聚体。与 MauG 不同，其中两个氧化还原当量产生双 Fe 氧化还原态，然而，相同的合成类似物稳定了两个高铁血红素，每个血红素都与一个卟啉 π-阳离子自由基偶联。本研究强调了桥在电子通讯中可能发挥的作用。
