The mechanism of methanol oxidation by quinoprotein methanol dehydrogenase (MDH·PQQ) in combination with methanol (MDH·PQQ·methanol) involves Glu-171 general base removal of the hydroxyl proton of methanol in concert with hydride equivalent transfer to the quinone carbon of pyrroloquinoline quinone (PQQ) and rearrangement to hydroquinone (PQQH2) with release of formaldehyde. Molecular dynamics (MD) studies of the structures of MDH·PQQ·methanol in the presence of activator NH3 and inhibitor have been carried out. In the MD structure of MDH·PQQ·methanol·NH3, the hydrated NH3 resides at a distance of ≈24 Å away from methanol and the ortho-quinone portion of PQQ. As such, influence of NH3 on the oxidation reaction is not probable. We find that competes with the substrate by hydrogen-bonding to Glu-171 such that the complex is not reactive. Ammonia readily forms imines with quinone. Imines are present in solution as neutral () and protonated () species. MD simulations establish that the derivative of structure is unreactive because of the nonproductive means of methanol binding. The structure obtained by the MD simulations with the neutral imine of MDH·PQQ(NH)·methanol structure is similar to the reactive MDH·PQQ·methanol complex. This active site geometry allows for catalysis of hydride equivalent transfer to the of PQQ(NH) by concerted Glu-171 general-base removal of the H alt="An external file that holds a picture, illustration, etc.
Object name is cjs0807.jpg" src="/pmc/articles/PMC528780/bin/cjs0807.jpg" />OCH3 proton and Arg-324 alt="An external file that holds a picture, illustration, etc.
Object name is cjs0807.jpg" src="/pmc/articles/PMC528780/bin/cjs0807.jpg" />H+ general-acid proton transfer to the imine nitrogen. Enzyme-bound alt="An external file that holds a picture, illustration, etc.
Object name is 15887_m07.jpg" src="/pmc/articles/PMC528780/bin/15887_m07.jpg" /> derivative of PQQ [PQQ(NH)] and CH2O product are formed.
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机译：喹蛋白甲醇脱氢酶（MDH·PQQ）与甲醇（MDH·PQQ·甲醇）结合作用的甲醇氧化机理涉及Glu-171除去甲醇的羟基质子与氢化物等价转移至吡咯并喹啉醌碳的Glu-171通用碱去除醌（PQQ）并重排为氢醌（PQQH2），并释放甲醛。在活化剂NH3和抑制剂存在下，对MDH·PQQ·甲醇的结构进行了分子动力学研究。在MDH·PQQ·甲醇·NH3的MD结构中，水合NH3与甲醇和PQQ的邻醌部分的距离约为≈24Å。这样，NH 3对氧化反应的影响是不可能的。我们发现通过与氢键合到Glu-171与底物竞争，从而使配合物不具有反应性。氨容易与醌形成亚胺。亚胺以中性和质子化形式存在于溶液中。 MD模拟证实，由于甲醇结合的非生产性手段，结构的衍生物是无反应的。通过MDH·PQQ（NH）·甲醇中性亚胺的MD模拟得到的结构与反应性MDH·PQQ·甲醇络合物相似。这种活动部位的几何形状允许通过协调一致的Glu-171通用碱基清除H alt =“将图片，插图等保存在外部文件中，从而将氢化物等效物转移到PQQ（NH）。对象名称为cjs0807.jpg“ src =” / pmc / articles / PMC528780 / bin / cjs0807.jpg“ /> OCH3质子和Arg-324 alt =”保存图片，插图等的外部文件。对象名称为cjs0807.jpg“ src =” / pmc / articles / PMC528780 / bin / cjs0807.jpg“ /> H + 普通酸质子转移至亚胺氮。酶结合的 alt =“包含图片，插图等的外部文件。形成PQQ [PQQ（NH）]的衍生物和CH2O产品的对象名称为15887_m07.jpg“ src =” / pmc / articles / PMC528780 / bin / 15887_m07.jpg“ />。
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