Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Institute of Theoretical Chemistry, School of Chemistry & Chemical Engineering, Shandong University, Jinan, 250100, PR China.
J Phys Chem B. 2012 Oct 4;116(39):11837-44. doi: 10.1021/jp305454m. Epub 2012 Sep 24.
The hydroxyethylphosphonate dioxygenase (HEPD) catalyzes the critical carbon-carbon bond cleavage step in the phosphinothricin (PT) biosynthetic pathway. The experimental research suggests that water molecules play an important role in the catalytic reaction process of HEPD. This work proposes a water involved reaction mechanism where water molecules serve as an oxygen source in the generation of mononuclear nonheme iron oxo complexes. These molecules can take part in the catalytic cycle before the carbon-carbon bond cleavage process. The properties of trapped water molecules are also discussed. Meanwhile, water molecules seem to be responsible for converting the reactive hydroxyl radical group ((-)OH) to the ferric hydroxide (Fe(III)-OH) in a specific way. This converting reaction may prevent the enzyme from damages caused by the hydroxyl radical groups. So, water molecules may serve as biological catalysts just like the work in the heme enzyme P450 StaP. This work could provide a better interpretation on how the intermediates interact with water molecules and a further understanding on the O(18) label experimental evidence in which only a relatively smaller ratio of oxygen atoms in water molecules (∼40%) are incorporated into the final product HMP.
羟乙基膦酸二加氧酶（HEPD）催化膦丝菌素（PT）生物合成途径中的关键碳-碳键断裂步骤。实验研究表明，水分子在 HEPD 的催化反应过程中起着重要作用。这项工作提出了一个涉及水分子的反应机制，其中水分子作为单核非血红素铁氧复合物生成的氧源。这些分子可以在碳-碳键断裂过程之前参与催化循环。还讨论了被捕获水分子的性质。同时，水分子似乎负责以特定的方式将反应性羟基自由基（(-)OH）转化为氢氧化铁（Fe(III)-OH）。这种转化反应可以防止酶受到羟基自由基的损伤。因此，水分子可能像血红素酶 P450 StaP 中的作用一样，充当生物催化剂。这项工作可以更好地解释中间体如何与水分子相互作用，并进一步了解 O(18) 标记实验证据，其中只有水分子中相对较小比例的氧原子（约 40%）被掺入最终产物 HMP 中。
