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A new route towards phenol production by one-step selective hydroxylation of benzene with hydrogen peroxide over ultrafine titanium silicalites-1 (TS-1) in a submerged ceramic membrane reactor was deve... 相似文献
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Mantri M Loik ND Hamed RB Claridge TD McCullagh JS Schofield CJ 《Chembiochem : a European journal of chemical biology》2011,12(4):531-534
Amino acid analyses reveal that JMJD6-catalysed hydroxylation of RNA-splicing regulatory protein fragments occurs to give hydroxylysine products with 5S stereochemistry. This contrasts with collagen lysyl hydroxylases, which give 5R-hydroxylated products. The work suggests that more than one subfamily of lysyl hydroxylases has evolved and illustrates the importance of stereochemical assignments in proteomic analyses. 相似文献
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Shuhong Mao Boyuan Hua Na Wang Xiaojie HU Zhijiang Ge Yanqing Li Sha Liu Fuping Lu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(2):287-292
BACKGROUND: The improved efficiency of steroid biotransformation using the biphasic system is generally attributed to the positive effect on the solubility of substrate in aqueous media. A promising alternative for the application of organic solvents in biphasic systems is the use of ionic liquids (ILs). This study aims to investigate the applicability of the biphasic ILs/water system for 11α hydroxylation of 16α, 17‐epoxyprogesterone (HEP) by Aspergillus ochraceus. RESULTS: Of the seven ILs tested, [C3mim][PF6] exhibited the best biocompatibility, with markedly improved biotransformation efficiency. In the [C3mim][PF6]‐based biphasic system, substrate conversion reached 90% under the condition in which buffer pH, volume ratio of buffer to ILs, cell concentration, and substrate concentration were 4.8, 10/1, 165 g L?1 and 20 g L?1, respectively. This is more efficient than that of the monophasic aqueous system. The effects of the cations and anions of these ILs on the 11α hydroxylation of 16α, 17‐epoxyprogesterone (HEP) by A. ochraceus is also discussed. CONCLUSION: The above results showed that IL/water biphasic system improved the efficiency of 11α hydroxylation of 16α, 17‐epoxyprogesterone (HEP) by A. ochraceus, thus suggesting the potential industrial application of ILs‐based biphasic systems for steroid biotransformation. © 2012 Society of Chemical Industry 相似文献
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Hideyuki Inui Toshimasa Itoh Keiko Yamamoto Shin-Ichi Ikushiro Toshiyuki Sakaki 《International journal of molecular sciences》2014,15(8):14044-14057
Polychlorinated dibenzo-p-dioxins (PCDDs) and coplanar polychlorinated biphenyls (PCBs) contribute to dioxin toxicity in humans and wildlife after bioaccumulation through the food chain from the environment. The authors examined human and rat cytochrome P450 (CYP)-dependent metabolism of PCDDs and PCBs. A number of human CYP isoforms belonging to the CYP1 and CYP2 families showed remarkable activities toward low-chlorinated PCDDs. In particular, human CYP1A1, CYP1A2, and CYP1B1 showed high activities toward monoCDDs, diCDDs, and triCDDs but no detectable activity toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD). Large amino acids located at putative substrate-recognition sites and the F-G loop in rat CYP1A1 contributed to the successful metabolism of 2,3,7,8-tetraCDD. Rat, but not human, CYP1A1 metabolized 3,3'',4,4'',5-pentachlorobiphenyl (CB126) to two hydroxylated metabolites. These metabolites are probably less toxic than is CB126, due to their higher solubility. Homology models of human and rat CYP1A1s and CB126 docking studies indicated that two amino acid differences in the CB126-binding cavity were important for CB126 metabolism. In this review, the importance of CYPs in the metabolism of dioxins and PCBs in mammals and the species-based differences between humans and rats are described. In addition, the authors reveal the molecular mechanism behind the binding modes of dioxins and PCBs in the heme pocket of CYPs. 相似文献
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为了达到增强硅气凝胶力学性能的目的,采用硅烷偶联剂KH550与KH560二步改性接枝玻璃纤维,进而制备纤维增强硅气凝胶。利用扫描电子显微镜、红外光谱仪、比表面及孔径分布仪、热重-差热分析仪、导热系数仪、电子动静态疲劳试验机等对其表征。实验结果表明:硅烷偶联剂改性玻璃纤维与硅气凝胶复合后网络结构更加均匀、骨架强度更加稳定、孔径多在30 nm以下、具有良好的热稳定性;同时,改性玻璃纤维的最佳添加量为20%(质量分数),此时其密度为0.167 g/cm3,导热系数为0.018 5 W/(m·K),接触角为127°,抗弯强度为1.042 MPa,抗压强度为0.669 MPa,达到预期实验目的。 相似文献
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采用水热法和尿素水解法首次合成了三元类水滑石CuNiAl(Cu+Ni/Al=3,Cu/Ni=5.0,3.0,1.0,0.33),将合成的类水滑石用于苯羟基化反应。采用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)和透射电镜(TEM)等手段对类水滑石进行表征,以CuNiAl31作为催化剂,考察了反应时间、反应温度、溶剂及溶剂用量、催化剂用量、n(benzene)/n(H_2O_2)对苯羟化反应的影响。结果表明:与CuNiAl11、CuNiAl21、CuNiAl13催化剂相比,CuNiAl31具有较高的反应活性,反应的最佳条件为:反应时间6h、反应温度65℃、15 ml吡啶作为溶剂、10mg催化剂、n(benzene)/n(H_2O_2)=3.0时,苯的转化率为7%,苯酚的选择性几乎为100%。 相似文献
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