微粒型甲烷單加氧酶(pMMO)是一個分布在細胞內脂質的一種酵素，它除了可以對甲烷進行加氧催化成甲醇外，它也可以對碳數較少且直鏈的碳氫烷類及烯類進行催化，但pMMO對於支鏈及含鹵素的烷類不具催化能力。氟的原子半徑雖略小於氫原子，但形成化合物後C-F鍵比C-H鍵或C-C鍵略長，這使得-CF3基的大小和異丙基相近。我們利用一端含-CF3的丙烷及丙烯作為pMMO的受質時，發現pMMO也可對於-CF3化合物進行氧化。

　　我們利用含銅離子濃度分別為0、20、40μM的基質所培養的細菌，分別對丁烷和戊烷進行氧化反應，對於丁烷和戊烷的氧化產物我們進行位置特異性同位素分析(PSIA)，我們利用一些不牽涉動力同位素效應的化學切割法，將末端碳切割下來，再利用氣相層析-燃燒-同位素比值質譜儀(GC-C-IRMS)偵測。由GC-C-IRMS偵測的結果，我們發現丁烷經嗜甲烷菌氧化後其二號碳上12C/13C碳穩定同位素效應為1.04，這表示sMMO或pMMO對於丁烷的二號碳的氧化是具有動力同位素效應。至於戊烷的氧化物中我們發現2-戊醇是主要的產物，同時也發現少量的3-戊醇，戊烷比丁烷多一個碳，在裂片的切割上比丁烷來得複雜，因此對於戊烷的分子內碳穩定同位素的分析還需更進一步取得裂片的資訊。

　Particulate methane monooxygenase (pMMO) from M. capsulatus (Bath) is an internal membrance protein which can catalyze the conversion of methane to methanol. Short normal alkanes and alkenes can also be oxidized to the corresponding alcohols or epoxides by this enzyme. According to the updated data, the hydrocarbon with branched chain or containing heteroatom can not be the substrates of pMMO. On the other hand, the size of fluorine atom is relatively smaller than hydrogen atom. The bond length of C-F is a little bit longer than C-H bond and C-C bond, hence, the size of perfluoro group is about the same as isopropyl group. Because of the dipole moment of perfluoro group is relatively smaller and more hydrophobic than the other heteroatom containing functional group. All these scenarios have allowed us to consider using perfluoro propane and propene as potential substrates for pMMO. In this study, we found that pMMO can oxidize the perfluoro propane and propene to obtain 1,1,1-trifluoro propan-2-ol and 2-(trifluoro)-oxirane, respectively. The -CF3 group is inductively electron-withdrawing group. These two newly found substrates for pMMO will assist to uncover the C-H activation mechanism of pMMO.

　The bacteria M. capsulatus (Bath) was grown in NMS buffer under three different copper concentration, which are 0, 20 and 40 M. These bacteria express soluble methane monooxygenase (sMMO) in the absence of copper(II) whereas switch to particulate methane monooxygenase expression at 20 and 40 M copper concentration. We facilitated these M. capsulatus (Bath) cells to oxidize butane and pentane molecules. The oxidation products are subjected for subsequent position specific stable 12C/13C isotope analysis (PSIA). To exploit designed chemical cleavge at specific carbon-carbon bond, we can shorten one carbon from the original butane and pentane. After GC-C-IRMS analysis, we found the oxidation 12C/13C kinetic isotope effect for C2 carbon is 1.04. Therefore, we concluded that there is a 12C/13C kinetic isotope effect for butane conversion to butan-2-ol mediated by either sMMO or pMMO. In terms of pentane molecule, pentan-2-ol is the major oxidative product while pentan-3-ol is less abundant. The chemical cleavage fragments is much more complicated than expected to be. We are on the way to obtain more detailed the corresponding GC-C-IRMS data to derive its 12C/13C kinetic isotope effect of pentane oxidation.

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