• Journal of Photoscience
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• 제7권1호
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• pp.15-19
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• 2000

The photochemical reaction mechanism has been investigated for methanol insertion into the p-substituted phenylketo carbenes. The triplet spin state of phenyl koto carbene is stabilized by the neighbored carbonyl electrons. When the phenylketo carbene reacts with methanol, the ylied intermediate is formed, then moves to the activated transition state.

• Bulletin of the Korean Chemical Society
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• 제29권12호
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• pp.2349-2354
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• 2008

• Journal of Microbiology and Biotechnology
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• 제30권8호
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• pp.1261-1271
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• 2020

Cytochrome c_L (Cytc_L) is an essential protein in the process of methanol oxidation in methylotrophs. It receives an electron from the pyrroloquinoline quinone (PQQ) cofactor of methanol dehydrogenase (MDH) to produce formaldehyde. The direct electron transfer mechanism between Cytc_L and MDH remains unknown due to the lack of structural information. To help gain a better understanding of the mechanism, we determined the first crystal structure of heme c containing Cytc_L from the aquatic methylotrophic bacterium Methylophaga aminisulfidivorans MP^T at 2.13 Å resolution. The crystal structure of Ma-Cytc_L revealed its unique features compared to those of the terrestrial homologues. Apart from Fe in heme, three additional metal ion binding sites for Na⁺, Ca⁺, and Fe²⁺ were found, wherein the ions mostly formed coordination bonds with the amino acid residues on the loop (G93-Y111) that interacts with heme. Therefore, these ions seemed to enhance the stability of heme insertion by increasing the loop's steadiness. The basic N-terminal end, together with helix α4 and loop (G126 to Y136), contributed positive charge to the region. In contrast, the acidic C-terminal end provided a negatively charged surface, yielding several electrostatic contact points with partner proteins for electron transfer. These exceptional features of Ma-Cytc_L, along with the structural information of MDH, led us to hypothesize the need for an adapter protein bridging MDH to Cytc_L within appropriate proximity for electron transfer. With this knowledge in mind, the methanol oxidation complex reconstitution in vitro could be utilized to produce metabolic intermediates at the industry level.

• Bulletin of the Korean Chemical Society
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• 제24권2호
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• pp.197-204
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• 2003

The intracluster ion-molecule reactions of $Ti^+(H_2O)_n,\;Ti^+(CH_3OCH_3)_n,\;and\;Ti^+(CH_3OD)_n$ complexes produced by the mixing of the laser-vaporized plasma and the pulsed supersonic beam were studied using a reflectron time-of-flight mass spectrometer. The reactions of $Ti^+$ with water clusters were dominated by the dehydrogenation reaction, which produces $TiO^+(H_2O)_n$ clusters. The mass spectra resulting from the reactions of $Ti^+\;with\;CH_3OCH_3$ clusters exhibit a major sequence of $Ti^+(OCH_3)_m(CH_3OCH_3)_n$ cluster ions, which is attributed to the insertion of $Ti^+$ ion into C-O bond of $CH_3OCH_3$ followed by $CH_3$ elimination. The prevalence of $Ti^+(OCH_3)_m(CH_3OD)_n$ ions in the reaction of $Ti^+\;with\;CH_3OD$ clusters suggests that D elimination via O-D bond insertion is the preferred decomposition pathway. In addition, the results indicate that consecutive insertion reactions by the $Ti^+$ ion occur for up to three precursor molecules. Thus, examination of $Ti^+$ insertion into three different molecules establishes the reactivity order: O-H > C-O > C-H. The experiments additionally show that the chemical reactivity of heterocluster ions is greatly influenced by cluster size and argon stagnation pressure. The reaction energetics and formation mechanisms of the observed heterocluster ions are also discussed.

• 대한화학회지
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• 제37권8호
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• pp.757-764
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• 1993

Phenylsilylene(PhHSi:)의 광분해 전구체인, 1,1,1,3,3,3-hexamethyl-2-phenyltrisilane(2)과 2,3-dicarbomethoxy-1,4,5,6,7-pentaphenyl-7-silanorbornadiene(5)을 10%와 73%의 수율로 각각 합성하였다. 전구체 2를 254 nm의 빛을 조사시켜 광분해 실험시킨 결과 triethylsilane 존재하에서는 phenylsilylene이 Si-H 결합에 삽입된 생성물인 1,1,1-triethyl-2-phenyldisilane (6)이 44%의 수율로 얻어졌고, diphenylacetylene 존재하에서는 phenylsilylene이 삼중결합에 첨가된 후 diphenylacetylene과 [2＋2] 첨가반응이 일어나 얻어진 생성물, 1-phenyl-1-silacyclopenta-2,4-diene(4)과 phenyl-silylene이 삼중결합에 첨가된 다음 곧 이합체화되어진 화합물인 1,2-diphenyl-1,2-disilacyclohexa-2,5-diene(10)이 각각 68% 와 26%의 수율로 얻어졌다. Neat 광반응에서는 생성된 phenylsilylene이 분자간 C-H 삽입반응을 하여 생성된 화합물, 1,5-dihydrosilanthren(11)과 전구체 2가 Si-H 결합에 삽입된 화합물, 1,2-diphenyltrisilane(12)이 5%와 7%의 수율로 각각 얻어졌다. 같은 조건에서 화합물 5를 triethylsilane과 methanol 존재하에서 광분해시킨 결과 phenylsilylene은 생성되지 않고 분자내 1,5-sigmatropic 자리옮김에 의한 silylenolether가 생성됨을 확인하였다.

• 한국항공우주학회지
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• 제41권4호
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• pp.299-304
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• 2013

이온성 액체 추진제인 HAN은 무독성의 높은 저장성을 갖는 단일 추진제로서 메탄올을 혼합하여 비추력을 향상시켜 하이드라진을 대체할 수 있을 있다. HAN은 하이드록실아민과 질산의 산-염기 반응을 통해 합성하며, 메탄올과 8.2:1의 비율로 혼합한다. HAN의 분해를 위해서 이리듐 촉매를 사용하며, 하나의 오리피스를 갖는 1 N급 추력기를 사용하여 HAN/메탄올 추진제의 성능 평가를 수행하였다. 메탄올 연소로 인해 반응 생성물의 온도가 높기 때문에 디스트리뷰터의 열적 안정성을 향상시키기 위해 세라믹 재료를 적용하였다. 완전한 분해를 위해서는 최소 $400^{\circ}C$의 예열 온도를 필요로 하였다. 높은 $C^*$ 효율을 얻기 위해서는 가압 압력이 높아져야 했으며, 이로 인해 촉매 상단의 분해 성능이 저하되면서 전체 추력기 성능 저하가 유발되었다. 이를 해결하기 위해 미세한 금속 메쉬를 인젝터 후단에 삽입하여 추진제의 분무 특성을 향상시켰으며, 실험 결과 촉매의 성능 저하 현상이 개선되었음을 확인하였다.