【作者】 刘懿；

【导师】 魏俊发；

【作者基本信息】 陕西师范大学 ， 有机化学， 2002， 硕士

【摘要】 甲烷单加氧酶（MMO）是甲烷利用菌在代谢过程中的一种重要酶系。作为生物体中唯一能够在常温常压下实现甲烷的选择性氧化的酶，MMO为探索甲烷的催化氧化提供了理想的催化剂模型。并且，MMO是一种非专一性的、具有广泛应用前景的工业生物催化剂，能催化C₁—C₂0各种取代烃的羟基化反应与C2—C10各种取代烯烃的环氧化反应。另外，MMO在医药与工业方面亦有很重要的应用前景。MMO的优越性使它成为研究热点所在。本文就MMO及其化学模拟研究做一系统评述。 本文首先介绍了MMO的来源、结构、光谱性质和作用。MMO有两种存在形式：颗粒性甲烷单加氧酶（pMMO）和可溶性甲烷单加氧酶（sMMO）。目前研究主要集中在sMMO方面。它由羟基化酶（MMOH）、调节蛋白（MMOB）和还原蛋白（MMOR）三部分构成。MMOH是MMO的关键组分，含a、β和y三个亚基。MMOH活性部位位于。亚基α为一含有羧基桥联的双铁核中心，是分子氧O2的活化与烃类C-H的羟基化反应发生地方。 以MMO活性中心为依据，可以合成贴近MMO结构的小分子模型配合物，这对于认识天然MMO的复杂结构、功能、催化机制继而认识生命现象具有重要意义。同时，对工业上开发用于烃类选择氧化的仿生催化剂具有重要意义。因此，MMO及模拟物的研究已成为生命科学与化学研究中富有挑战性、非常活跃的前沿课题。在这方面S．J．Lippard、L. Que，Jr、M．Suzuki等领导的实验室取得了许多开创性的研究成果。 MMO的化学模拟研究可以分为结构模拟与功能模拟两个方面。在对MMOH活性部位的结构模拟研究中，许多配体成功地运用于合成双铁核配合物之中，例如H2hbab、Biphme、XOK、tmen等。结构模拟工作的重点在于模拟MMO结构参数、光谱参数和催化过程中所特有的中间体方面，例如对中间体P与Q的模拟，P被认为有Fe2TM（μ-O2）结构，而Q则含有Fe2TM（μ-O）2核。Kitajima等1990年用单铁核化合物Fen{HB（3,5-iPr2Pz）3（O2CR）}（CH3CN）与O2反应生成了Fe2m（μ-1，2—O2）结构的化合物。Y.Dong等用[Fe2L（O2C6H5）]X2（L=HPTB、N-Et-HPTB、HPTP）与O2反应模拟MMOH-P结构，Suzuki等亦用[Fe2L（RCO2）（L=Tpdp、MeTtpdp、Me上tpdp）与 o。反应对 P进行模拟。这些研究得到了许多重要结论：首先，金属中心配位不饱和将有利于OZ的键合；其次，立体因素与电子因素也影响双氧加合物的稳定性。例如采用新型桥配体HZXDK，由于其中富含梭酸基，在合成 Fez’‘赚拟物方面具有较大优势，其双铁核配合物比上述含 N多的配体，能够更好地再现MMO及y的活性部位。含不同XDK的双铁核配合物m、氏B皿K)彼成功地应用于与OZ反应而模拟MMOHI中。含有Fe。…－O)。、Fe。…－O)o－OH)和Fe。…－O)…－H3Oz)核的报道也较多，所使用的配体多为TPA及其衍生配体。首例具有Fe。V－Oh及Fe。…－O)…－OH)核的模型配合物分别为［F＊2’‘’…－O)ZWMC。－TPA］（CIO。）2与 FCZty－O)…－O切（6－M＊。－TpA）（CIO4）3。【Fe”‘FeI＊…－O)。（5－Me3－TpA）］（CIO。）3与 FC’nF＊‘＊…－O)2（－Me－TpA）2（CIO4）可以作为MMOH－Q与 RNR RZ－X两种反应活性中间体的模拟。 在MMO功能模拟方面，有许多种含Fe配合物被应用于催化烷烃羟基化反应中，这方面研究较为系统、深入的属Fe厂PA)系统。Fe（TP）系统催化烃类氧化反应受诸多条件限制，配合物中Fe的价态、氧化剂的种类、氧化剂加入量及加入方式、配体立体结构等均对反应结果有很大的影响，使得此类体系十分复杂，同时也十分丰富。这方面的研究多是涉及反应机理，而机理亦是寻找一种真正的氧化中间体，常见的中间体有Fe”二O与BuO·（用TBPH为氧化剂）等。该部分还讨论了H。O。为氧化剂的体系以及Fez模型配合物催化亚碘酞苯对烯烃环氧化反应的情形。我们实验室报道了一系列MMO的手性模型配合物，并在烯烃的不对称催化环氧化方面取得了一些令人鼓舞的成果。更多还原

【Abstract】 Progress on Methane Monooxygenase and Its Model ComplexesLiuYiAbstract: Methane monooxygenase(MMO) is one of the most important enzymes during the metabolism of methantrophs. It is the only enzyme that can realize the selective oxidation of methane at the ordinary temperature and pressure and supply the ideal model for selective, partial oxidation of methane. Meanwhile, as a non-special biocatalyst, MMO can catalyze hydroxylation of all kinds of alkanes from Cj to €20 and epoxidation of alkenes from €2 to Qoas well. In addition, it has wide potential application in medicine and industry. It is just its advantage that makes it a hot area in research works.There are two forms of MMO exist natrually. One is the particulate, membrane-bound (pMMO) form and the other is the soluble (sMMO) form. The later consists of three components such as MMOH, MMOB, and MMOR. MMOH is the most important component, which consists of three subunits a, P, and 7. The active site, located at the a-subunit, contains a carboxylate-bridged diiron core where the activition of O2 and hydroxylation of C-H bond take place.Based on the structure of active site of MMO, a lot of small molecule model complexes analog with different diiron cores have been synthesized for the purpose of understanding the structure and catalytic properties of MMO in biological oxidation, and further, the biological phenomena of life. The structural and functional mimicing of MMO with binuclear iron complexes have been an active frontier and a challenge in biology and chemistry. In this aspect, many creative research works have been done in the passed decade, especially those in the laboratories leaded by S. J. Lippard, L. Que, Jr., and M. Suzuki, and elsewhere.The researches on mimicing of MMO can be divided into structural and functional mimic. A great many dinuclear iron complexes have been synthesized for the structural mimics of MMOH with the ligands including F^Hbab, BiphMe, XDK, tmen, and so on. The mimic of the active intermediate, MMOH-P and -Q, during the catalytic process is always an important topic. MMOH-P is considered as an active intermediate with an Fei’^-Oi) core and Q with an Fe2IV(/*-O)2 core. The firstMMOH-P intermediate analog, Fe2IH(a-l,2-O2), was obtained from the reaction of a mononuclear iron complex [FeI1{HB(3,5-iPr2Pz)3(O2CR)}(CH3CN) and O2 by N. Kitajima in 1990. MMOH-P mimics via [Fe2lIL(O2CC6H5)X2](L=HPTB, A^-Et-HPTB, or HPTP) with O2 and [Fe2"(RCO2)L](BF4)2 [L = tpdp, Me2-tpdp, or Me4-tpdp] with O2 have been also reported. Many useful conclusions can be drawn from these reactions. Firstly, the unsaturated coordination of metal center is favorable to the bonding of O2. Secondly, the steric and electronic factors also affect the stability of O2-adducts.A new ligand, H2XDK, has more advantages in synthesizing the Fe2H complexes due to it has more carboxylic groups than the ligands with N atoms. The diiron complexes with this ligand can reproduce nicely the active site of MMO and RNR. Recently, various diferric complexes with XDK, HPXDK, and HBXDK have been successfully applied to the reaction with O2 for mimicing MMOH-P. Many complexes with an Fe2C"-O)2, Fe2(/*-O)(//-OH), or Fe2(u-O)(^-Hs02) core have been reported with ligands of TPA and its derivatives. The first complex containing Fe2(?O)2 core is [Fe21’ICu-O)2(6-Me3-TPA)](ClO4)2 and the complex containing Fe2(yU-O)C?OH) is [Fe2Gu-O)Gu-OH)(6-Me3-TPA)](ClO4)3. The most close mimics of MMOH-Q and RNR R2-X maybe [FemFelv(/z-O)2(5-Me3-TPA)](ClO4)3 and [Fe10Felv(^-O)2(6-Me-TPA)]2 (C104)3 ?In the aspect of functional mimic of MMO, many diiron complexes have been used in the reaction of catalytic hydroxylation of alkanes. Among which the Fe(TPA) systems have been thoroughly investigated. There are many factors affect the catalytic activity of the hydroxylation of alkanes. This makes the catalyic system more complex and, in turn, more plenty. The research is focus on the reaction mechanism to find out the true oxidant. A free radical BuO- derived from BuOOH (TBHP) an更多还原