Cytochromes P450 are versatile heme-based enzymes responsible for vital life processes. Of these, P450cam (substrate camphor) has been most studied. Despite this, precise mechanisms of the key O─O cleavage step remain partly elusive to date; effects observed in various enzyme mutants remain partly unexplained. We have carried out extended (to 1000 ns) MM-MD and follow-on quantum mechanics/molecular mechanics computations, both on the well-studied FeOO state and on Cpd(0) (compound 0). Our simulations include (all camphor-bound): (a) WT (wild type), FeOO state. (b) WT, Cpd(0). (c) Pdx (Putidaredoxin, redox partner of P450)-docked-WT, FeOO state. (d) Pdx-docked WT, Cpd(0). (e) Pdx-docked T252A mutant, Cpd(0). Among our key findings: (a) Effect of Pdx docking appears to go far beyond that indicated in prior studies: it leads to specific alterations in secondary structure that create the crucial proton relay network. (b) Specific proton relay networks we identify are: FeOO(H)⋯T252⋯nH 2 O⋯D251 in WT; FeOO(H)⋯nH 2 O⋯D251 in T252A mutant; both occur with Pdx docking. (c) Direct interaction of D251 with -FeOOH is, respectively, rare/frequent in WT/T252A mutant. (d) In WT, T252 is in the proton relay network. (e) Positioning of camphor appears significant: when camphor is part of H-bonding network, second protonation appears to be facilitated.

中文翻译：

---

P450cam中的质子中继网络是在与普达氧还蛋白对接后形成的。

细胞色素P450是多用途的基于血红素的酶，负责生命的关键过程。其中，对P450cam（底物樟脑）的研究最多。尽管如此，迄今为止，关键的O-O裂解步骤的精确机制仍然部分难以捉摸。在各种酶突变体中观察到的效应尚不能部分解释。我们已经对FeOO态和Cpd（0）（化合物0）进行了扩展（至1000 ns）的MM-MD和后续的量子力学/分子力学计算。我们的模拟包括（所有樟脑结合的）：（a）WT（野生型），FeOO状态。（b）WT，Cpd（0）。（c）Pdx（Putidaredoxin，P450的氧化还原伴侣）-FeOO州的WT码头。（d）以Pdx固定的WT，Cpd（0）。（e）以Pdx为底的T252A突变体Cpd（0）。在我们的主要发现中：（a）Pdx对接的效果似乎远远超出了先前研究中表明的效果：它会导致二级结构发生特定变化，从而形成至关重要的质子中继网络。（b）我们确定的特定质子中继网络为：WT中的FeOO（H）⋯T252⋯nH 2 O⋯D251；T252A突变体中的FeOO（H）⋯nH 2 O⋯D251; 两者都与Pdx对接一起发生。（c）在WT / T252A突变体中，D251与-FeOOH的直接相互作用分别是罕见/频繁的。（d）在WT中，T252在质子中继网络中。（e）樟脑的位置似乎很重要：当樟脑是氢键网络的一部分时，似乎可以促进第二次质子化。T252在质子中继网络中。（e）樟脑的位置似乎很重要：当樟脑是氢键网络的一部分时，似乎可以促进第二次质子化。T252在质子中继网络中。（e）樟脑的位置似乎很重要：当樟脑是氢键网络的一部分时，似乎可以促进第二次质子化。