Reaction Mechanism of the Bicopper Enzyme Peptidylglycine α-Hydroxylating Monooxygenase
Reaction Mechanism of the Bicopper Enzyme Peptidylglycine α-Hydroxylating Monooxygenase
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DOI：
10.1074/jbc.m114.558494
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发表时间：
2014-05-16
影响因子：
4.8
通讯作者：
Kaestner, Johannes
中科院分区：
文献类型：
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作者：
Abad, Enrique;Rommel, Judith B.;Kaestner, Johannes
背景资料：肽酰甘氨酸-羟基化单加氧酶催化肽激素、神经递质和生长因子的C-末端羧酰胺的产生以用于生物活化。结果：我们比较了几种可能的反应机制，通过量子力学/分子力学计算。结论：[CuOOH]（2+）是最有可能的络合物。重要性：我们的计算研究提出了一个新的机制，这解释了实验观察.肽酰甘氨酸-羟基化单加氧酶是一个非相互作用的双铜酶，立体特异性羟基化末端甘氨酸的小肽，其后来的酰胺化。神经内分泌信使，如催产素，依赖于这种酶的生物活性。每一次催化转换都需要一个氧分子、两个来自溶剂的质子和两个电子。尽管该酶已被广泛研究，但关于其反应机理尚未达成共识，实验和理论研究倾向于pro-S夺取氢原子，然后重新结合OH基团。然而，已经假设了几种夺氢物种;因为在反应期间消耗了两个质子，所以可以获得几种质子化状态。铜原子之间的电子转移也可能对催化作用起着至关重要的作用。这导致了六种可能的抽象物种。在本研究中，我们将它们放在平等的基础上进行比较。我们进行量子力学/分子力学计算，考虑甘氨酸的氢提取。我们的研究结果表明，最有可能的机制是质子化的抽象物种之前的氢抽象和另一个质子化，以及减少OH重新绑定。
Background: Peptidylglycine -hydroxylating monooxygenase catalyzes the generation of C-terminal carboxamides of peptide hormones, neurotransmitters, and growth factors for biological activation. Results: We compare several possible reaction mechanisms by means of quantum mechanics/molecular mechanics calculations. Conclusion: Our results suggest that the most likely abstracting species is [CuOOH](2+). Significance: Our computational study proposes a new mechanism, which explains the experimental observations.Peptidylglycine -hydroxylating monooxygenase is a noninteracting bicopper enzyme that stereospecifically hydroxylates the terminal glycine of small peptides for its later amidation. Neuroendocrine messengers, such as oxytocin, rely on the biological activity of this enzyme. Each catalytic turnover requires one oxygen molecule, two protons from the solvent, and two electrons. Despite this enzyme having been widely studied, a consensus on the reaction mechanism has not yet been found. Experiments and theoretical studies favor a pro-S abstraction of a hydrogen atom followed by the rebinding of an OH group. However, several hydrogen-abstracting species have been postulated; because two protons are consumed during the reaction, several protonation states are available. An electron transfer between the copper atoms could play a crucial role for the catalysis as well. This leads to six possible abstracting species. In this study, we compare them on equal footing. We perform quantum mechanics/molecular mechanics calculations, considering the glycine hydrogen abstraction. Our results suggest that the most likely mechanism is a protonation of the abstracting species before the hydrogen abstraction and another protonation as well as a reduction before OH rebinding.