研究成果:泛素化於溶小體功能與品管的影響

 

泛素化於溶小體功能與品管的影響
Selective ubiquitination in lysophagy, lysosome maintenance, and lysosomal disorders

計畫成果摘要
泛素化被認為是控制受質被細胞自噬分解的關鍵。我們在先前的實驗已經發現,受損的溶小體會被泛素化,接著被細胞自噬蛋白辨識,最後進而被分解。但是負責將受損的溶小體泛素化的泛素蛋白酶目前尚未被發現。利用這個計畫的資助我們試圖利用APEX的方式來找出可能幫助受損的溶小體泛素化的泛素蛋白酶。目前我們已經找出幾個可能的泛素蛋白酶,所以將會在未來利用各種實驗方法驗證他們在受損的溶小體被泛素化中扮演的確切角色。

Project abstract
Ubiquitination has been implicated as a key signal for the selective degradation of substrates through autophagy. We have previously discovered that damaged lysosomes undergo selective ubiquitination, recruit autophagic adaptors, and are eventually turned over through that autophagic pathway (termed lysophagy). It however remains unknown what ubiquitin ligases mediate this degradation pathway. With the help of this grant and others we attempted to develop an APEX-based strategy to identify the ubiquitin ligases involved. Using this strategy we identified a panel of candidates that may be responsible for lysophagy. These candidates will be subjected to future testing for complete understanding of the lysophagy pathway.

 

 

研究成果:發展催化劑能在常溫常壓下有效能地轉換甲烷至甲醇

 

發展催化劑能在常溫常壓下有效能地轉換甲烷至甲醇
Develop a catalyst for catalytic conversion of methane into methanol efficiently under ambient conditions

The conversion of methane into methanol is very difficult chemistry requiring catalysts operating at elevated temperatures and pressures. The prospects of a future methanol economy depend on the successful development of robust and efficient catalysts that can accomplish this chemistry under mild conditions. In nature, the particulate methane monooxygenase (pMMO), a membrane-bound metalloenzyme, catalyzes methane oxidation with total selectivity and atom efficiency. Inspired by what we have learned about the pMMO over the past two decades, a tricopper complex [CuICuICuI(7-N-Etppz)]1+, where 7-N-Etppz stands for the organic ligand 3,30-(1,4-diazepane-1,4-diyl)bis[1-(4-ethylpiperazine-1-yl)propan-2-ol] based on the catalytic site of this enzyme has been developed and shown to mediate methane oxidation to methanol selectively. However, as a homogeneous catalyst, the catalytic efficiency and product yield are low because of the low solubility of methane in the solvent supporting the catalyst.

To overcome the problem of methane solubility in the catalytic system and to further improves the product yield. We re-formulated the tricopper cluster complex as a heterogeneous catalytic system assembled by immobilizing the tricopper cluster complex into mesoporous silica nanoparticles (MSNs) to take advantage of the “over solubility” of methane in liquids confined in nanoporous materials relative to the bulk solubility. For these gases, the interactions of the gas molecules with the nanoporous solid or with the solvent are significantly weaker than the interactions of the solvent molecules with the walls of the confining host framework. The stronger solvent–solid interactions create regions of low solvent density in the confined solvent, enhancing gas uptakes like CH4 and O2. The much higher solubility of methane within the pores of the mesoporous silica nanoparticles, as compared to the bulk solubility, led to very efficient turnover of the concentrated confined methane. Thus, the heterogeneous formulation exhibits dramatically higher catalytic efficiencies and turnover numbers, with commensurate improvements in chemical yields, offering the most proficient catalyst for the selective conversion of methane into methanol at room temperature developed to date. In this manner, we can drive the conversion of methane into methanol with hydrogen peroxide with a catalytic efficiency approaching 100%, as well as with high energy and atom economy under ambient methane pressures. The heterogeneous catalyst is robust and reuseable at least three reaction cycles. The samples are easily separated from the reaction mixture and dried under vacuum after each reaction cycle before performing the next run. This technology will lead to an economic process for methanol production that could have potential for further commercial applications.

 


 

直接轉化甲烷至甲醇是十分困難的化學反應,通常需要操作於高溫高壓的條件下而在未來甲醇經濟(是一種提議中未來的經濟形式,使用甲醇來代替現在廣泛使用的化石燃料來用作能量存儲,地面交通燃料,以及合成碳氫化合物的原料及其產品)的前景取決於是否能研發出強壯以及高效率的催化劑,能於常溫常壓下轉化甲烷為甲醇。然而在大自然中,普遍存在於嗜甲烷菌中的細胞質內膜上的微粒體型甲烷單氧化酵素(pMMO)卻可在常溫下高選擇性轉換甲烷為甲醇從過去二十年研究微粒體型甲烷單氧化酵素所學的知識並模擬其酵素活性中心的結構所合成出的三銅金屬錯合物[CuICuICuI(7-N-Etppz)]1+,可以於常溫常壓下高選擇性地執行甲烷至甲醇的反應然而這種昀相催化劑的催化效率以及甲醇的產率仍然十分低,最主要的原因是甲烷在有機溶劑中的溶解度十分低所致

為了改善甲烷氣體在催化系統中的溶解度,以近一步提高甲醇的產率,我們將三銅金屬錯合物負載於官能基化的中孔洞二氧化矽奈米球材料的垂直孔道中,利用”過度溶解度”的特性來大幅度提升被限制於奈米孔洞中的甲烷的溶解度在限制空間中,由於非極性的甲烷氣體分子與奈米孔洞內壁以及溶劑之間的作用力顯著的弱於溶劑分子與奈米孔洞內壁骨架間的作用力,而這溶劑與骨架間的強作用力造成許多區域的溶劑分子濃度較低但非極性氣體分子的濃度大幅提高(例如氧氣及甲烷)高濃度的甲烷分子貯存於二氧化矽奈米球的孔洞中,可以顯著的提升甲烷的催化效率以及轉換數,有效率的提升產物甲醇的產率,並有可能發展成為至今最有效率的高選擇性常溫常壓下轉換甲烷為甲醇的催化劑此異相催化劑甚至可以達到百分之百轉換甲烷為甲醇,有很高的能量與原子的經濟性此外此催化劑也可以重複使用至少三次催化反應此項技術, 將邁向更經濟的直接甲烷氧化為甲醇的工業製程並十分有潛力於商業應用

研究成果:TDP-43蛋白片段寡聚物之生化及生醫研究

 

室溫量子自旋電子與聲子的媒合
Marriage of quantum spintronics and phononics at room temperature

In this project, we have ultilized the various techniques and experties of all PIs and co-PIs to develope the new research area of thermal transport on non-magnetic and magnetic nanowires. For the growth of magnetic nanowire of Mn-SiGe, we established a new method to introduce Mn gas precursors MnCl2 during the VLS nanowire growth in CVD, such that Mn and Si atoms could be absorbed from the vapor phase by the Au-Si liquid catalysts and co-precipitated to form Si-Mn alloy nanowires. For the thermal transport probe, we have developed a new and sensitive probe based on the concept of thermal rectification. The thermal rectification in a pristine SiGe nanowire is shown in the inset of Fig. 1(a). The 4ω signals display a non-zero background which decreases with increasing Is,DC (or Ts,DC) as shown in Fig. 1(a). Regardless of the presence of the background, the absence of a peak at Is,DC=16μA indicates that there is no thermal rectification (R-1<0.2%). The result can be further verified by measuring 1ω and 2ω signals described above. As shown in Fig. 1(b), the 1ω/2ω signals vs. Ih,DC display a linear relation without a bump, which consistently indicate R-1<0.2% in the SiGe nanowire.

For the non-magnetic crystalline nanowire, Bi2-xSbxTe3 (BST) nanowires were grown directly from Bi0.5Sb1.5Te3 thin film by thermal annealing and the diameter dependence of thermoelectric properties of single BST NW has been in-situ studied in FIB trimming. The consequence implies the size and defect effects have more influence on phonon scattering than that of electron carriers in this diameter region. When the NW was further trimmed to 285 nm, both the electrical and thermal conductivities started a dramatic drop due to the formation of a large number of defects and the amorphous-like structure. The study not only provides the thoroughly understanding of the size and ion irradiation effects on the electrical and thermal transport properties but also provides a possible method to manipulate the physical properties in nanostructures for the extensive applications in engineering high ZT thermoelectric materials.

FIG. 1. (a) The signals at 4ω of a SiGe nanowire when gradually raising the Ts,DC of the sensor. The inset shows the SEM image of the SiGe nanowire anchored between a heater and a sensor. (b) The 1ω/2ω signals of the same sample when gradually raising the Th,DC of the heater. From the data and our analyses, we determine R-1<0.2%. (c), (d) The diameter dependent electrical, thermal conductivity, seebeck coefficient and figure of merit and of a FIB trimmed BST nanowire.

In the near future, we will further use this technique to explore the dynamic magnetism and the thermal properties of for the quasi-one dimensional magnetic nanowires.

 


 

本計劃中我們研究了摻雜錳元素於矽奈米線以將其變成磁性半導體的可能性,並探討了各種奈米線的熱傳導與熱整流性質。在生長磁性奈米線方面,我們提出了使用氣態MnCl2作為參與Au-Si液態催化反應以析出Si-Mn合金的方法。在熱傳導與熱整流性質的研究上,我們發明了利用4ω方法研究了諸多奈米線的熱整流性質。由於此新方法排除了以往量測熱功率的不確定性,因此比以前的方法更靈敏約十倍(如圖一a所示)。另外我們也開發了1ω/2ω的量測方法,並實驗證實這兩種方法得到一致的結果(如圖一b所示)。以圖一的矽鍺奈米線為例,我們的實驗結果確認其熱整流效應小於0.2%。這個實驗方法將對於介面與非對稱結構上的聲子與熱傳導研究有基礎的重要性。未來我們將利用本計劃所開發的技術與方法研究準一維磁性奈米線並探索基礎的動態磁學與熱傳導問題。

對於非磁性結晶納米線方面,Bi2-xSbxTe3(BST)奈米的成長以通過熱處理技術,直接從Bi0.5Sb1.5Te3薄膜生長,並且整合FIB修剪技術對單根BST NW的熱電性能的原位研究技術探究其物理特性與奈米線直徑之相依性。 結果顯示:尺寸和缺陷效應對聲子散射的影響比在該直徑區域中的電子載流子的影響更大,當NW修剪至285nm時,由於形成大量缺陷和非晶狀結構,電導率和熱導率開始顯著下降。 該研究不僅提供了對尺寸和離子輻射效應對電和熱傳輸性能的徹底理解,而且提供了操縱納米結構中的物理性質的可能方法,可廣泛應用於高ZT熱電材料。

圖一(a) 以4ω方法量測奈米線的熱整流性質。嵌入圖為懸空的矽鍺奈米線,兩端固定於微米熱傳導量測裝置的電子顯微鏡影像。(b)以1ω/2ω方法量測奈米線的熱整流性質。綜合圖一a與b的結果我們確認其熱整。(c), (d)電,熱導率,塞貝克係數和品質因數(ZT)於FIB修剪後BST納米線及其對直徑的相依性。