MOFs中合理構建人工雙核銅單加氧酶
作者：
小柯機器人發布時間：2021/1/10 19:45:40
美國芝加哥大學Wenbin Lin團隊報導了一種在MOFs中合理構建人工雙核銅單加氧酶的策略。 相關研究成果於2021年1月7日出版的《美國化學會志》。
人工酶系統被廣泛研究，以模擬其天然對應的結構和功能。然而，在這些人工體系中，結構模擬和催化活性之間仍然存在著很大的差距。
該文報導了一種從鈦金屬有機骨架（MOF）出發構建人工雙核銅單加氧酶的新方法。MIL-125（Ti）（MIL=Matériaux de l'Institut Lavoisier）的二級結構單元（SBU）上的氫氧化物基團的去質子化允許SBUs與具有緊密間隔的CuI對金屬化，這些CuI對被分子O2氧化以提供基於MOF的人工雙核單加氧酶Ti8-Cu2中的CuI2（μ2-OH）2輔因子。
研究人員還製備了人工單核銅單加氧酶Ti8-Cu1進行比較。採用熱重分析、電感耦合等離子體質譜、X射線吸收光譜、傅立葉變換紅外光譜和紫外-可見光譜對MOF基單加氧酶進行了表徵。在存在共沸物的情況下，Ti8-Cu2對一系列單加氧過程表現出優異的催化活性，包括環氧化、羥基化、Baeyer–Villiger氧化和硫氧化，轉化率高達3450。Ti8-Cu2比Ti8-Cu1的轉化率至少高17倍。
密度泛函理論計算表明，O2活化是單加氧反應的限速步驟。計算研究進一步表明，Ti8-Cu2中的Cu2位點協同穩定了用於O-O鍵斷裂的Cu-O2加合物，自由能增加比Ti8-Cu1中的單核Cu位小6.6 kcal/mol，說明Ti8-Cu2比Ti8-Cu1具有更高的催化活性。
附：英文原文
Title: Rational Construction of an Artificial Binuclear Copper Monooxygenase in a Metal–Organic Framework
Author: Xuanyu Feng, Yang Song, Justin S. Chen, Ziwan Xu, Soren J. Dunn, Wenbin Lin
Issue&Volume: January 7, 2021
Abstract: Artificial enzymatic systems are extensively studied to mimic the structures and functions of their natural counterparts. However, there remains a significant gap between structural modeling and catalytic activity in these artificial systems. Herein we report a novel strategy for the construction of an artificial binuclear copper monooxygenase starting from a Ti metal–organic framework (MOF). The deprotonation of the hydroxide groups on the secondary building units (SBUs) of MIL-125(Ti) (MIL = Matériaux de l』Institut Lavoisier) allows for the metalation of the SBUs with closely spaced CuI pairs, which are oxidized by molecular O2 to afford the CuII2(μ2-OH)2 cofactor in the MOF-based artificial binuclear monooxygenase Ti8-Cu2. An artificial mononuclear Cu monooxygenase Ti8-Cu1 was also prepared for comparison. The MOF-based monooxygenases were characterized by a combination of thermogravimetric analysis, inductively coupled plasma–mass spectrometry, X-ray absorption spectroscopy, Fourier-transform infrared spectroscopy, and UV–vis spectroscopy. In the presence of coreductants, Ti8-Cu2 exhibited outstanding catalytic activity toward a wide range of monooxygenation processes, including epoxidation, hydroxylation, Baeyer–Villiger oxidation, and sulfoxidation, with turnover numbers of up to 3450. Ti8-Cu2 showed a turnover frequency at least 17 times higher than that of Ti8-Cu1. Density functional theory calculations revealed O2 activation as the rate-limiting step in the monooxygenation processes. Computational studies further showed that the Cu2 sites in Ti8-Cu2 cooperatively stabilized the Cu–O2 adduct for O–O bond cleavage with 6.6 kcal/mol smaller free energy increase than that of the mononuclear Cu sites in Ti8-Cu1, accounting for the significantly higher catalytic activity of Ti8-Cu2 over Ti8-Cu1.
DOI: 10.1021/jacs.0c11920
Source: https://pubs.acs.org/doi/10.1021/jacs.0c11920