Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, 80401, USA.
National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado, 80401, USA.
Sci Rep. 2018 Aug 27;8(1):12826. doi: 10.1038/s41598-018-31237-4.
Biological routes to the production of fuels from renewable feedstocks hold significant promise in our efforts towards a sustainable future. The fatty acid decarboxylase enzyme (OleT) is a cytochrome P450 enzyme that converts long and medium chain fatty acids to terminal alkenes and shares significant similarities in terms of structure, substrate scope and mechanism with the hydroxylase cytochrome P450 (P450). Recent reports have demonstrated that catalytic pathways in these enzymes bifurcate when the heme is in its iron-hydroxo (compound II) state. In spite of significant similarities, the fundamental underpinnings of their different characteristic wild-type reactivities remain ambiguous. Here, we develop point charges, modified parameters and report molecular simulations of this crucial intermediate step. Water occupancies and substrate mobility at the active site are observed to be vital differentiating aspects between the two enzymes in the compound II state and corroborate recent experimental hypotheses. Apart from increased substrate mobility in the hydroxylase, which could have implications for enabling the rebound mechanism for hydroxylation, OleT is characterized by much stronger binding of the substrate carboxylate group to the active site arginine, implicating it as an important enabling actor for decarboxylation.
从可再生原料生产燃料的生物途径在我们迈向可持续未来的努力中具有巨大的潜力。脂肪酸脱羧酶（OleT）是一种细胞色素 P450 酶，可将长链和中链脂肪酸转化为末端烯烃，其结构、底物范围和机制与羟化细胞色素 P450（P450）有很大的相似性。最近的报告表明，当亚铁羟化物（复合物 II）状态下时，这些酶的催化途径会分叉。尽管有很大的相似性，但它们不同的野生型反应性的基本原理仍然不清楚。在这里，我们开发了点电荷、修改了参数，并报告了这个关键中间步骤的分子模拟。在复合物 II 状态下，观察到活性位点的水占据和底物的流动性是区分两种酶的重要因素，这与最近的实验假设相符。除了羟化酶中底物流动性的增加，这可能对促进羟化的回弹机制有影响外，OleT 的特点是其底物羧酸盐基团与活性位点精氨酸的结合更强，这暗示它是脱羧反应的一个重要促进因素。
