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81.
菊糖酶酵母去阻遏突变体的选育 总被引:1,自引:0,他引:1
魏文铃 《厦门大学学报(自然科学版)》1991,30(1):94-98
一株萨地假丝酵母(Candida Salmenticensis B—102)能产生菊糖酶(Inulinase)。经研究发现,这株酵母酶系统合成菊糖酶时受右旋糖、果糖的抑制。因此,应用固定化酵母细胞进行菊糖连续水解制备高果糖浆时,将受到限制。使用甲基磺酸乙酯(EMS)处理菌体细胞后,通过脱氧葡萄糖选择淘汰,分离到稳定的菊糖酶合成去阻遇突变体。测定了突变体的一些特性,并探讨诱变处理对菌体酶系统的影响。 相似文献
82.
84.
Weiqing Xu Yu Wu Xiaosi Wang Ying Qin Hengjia Wang Zhen Luo Prof. Jing Wen Prof. Liuyong Hu Prof. Wenling Gu Prof. Chengzhou Zhu 《Angewandte Chemie (International ed. in English)》2023,62(29):e202304625
Exploring advanced co-reaction accelerators with superior oxygen reduction activity that generate rich reactive oxygen species (ROS) has attracted great attention in boosting luminol-O2 electrochemiluminescence (ECL). However, tuning accelerators for efficient and selective catalytic O2 activation to switch anodic/cathodic ECL is very challenging. Herein, we report that enzyme-inspired Fe-based single-atom catalysts with axial N/C coordination structures (FeN5, FeN4© SACs) can generate specific ROS for cathodic/anodic ECL conversion. Mechanistic studies reveal that FeN5 sites prefer to produce highly active hydroxyl radicals and afford direct cathodic luminescence by promoting the cleavage of O−O bonds through N-induced electron redistribution. In contrast, FeN4© sites tend to produce superoxide radicals, resulting in inefficient anodic ECL. Benefiting from the enhanced cathodic ECL, FeN5 SAC-based immunosensor was constructed for the sensitive detection of cancer biomarkers. 相似文献
85.
Wang Ren Yantang Wang Qinhui He Yue Zhou Chunxin Li Wenling Wang 《Natural product research》2020,34(18):2581-2588
AbstractImmature dendritic cells (iDCs) play very important roles in the pathological process of rheumatoid arthritis (RA). Therefore, it is urgent to search for natural products with antiproliferative activity on iDCs for anti-RA drug discovery. Erycibe schmidtii, a traditional Chinese medicine, has been used to treat RA in China. Its bioactive ingredients on RA are still unclear. In this study, twenty compounds including a new caffeoylquinic acid derivative, 3-O-caffeoyl-4-O-syringoylquinic acid methyl ester (16), were isolated from E. schmidtii. Their structures were elucidated by NMR and mass spectroscopic analysis, and comparison with literature data. Seventeen compounds were obtained from this plant for the first time, and ten were first found from the genus Erycibe. Scopoletin (1, 5.0?μM) functionally reduced proliferation level of bone marrow immature dendritic cells (BM-iDCs) more than 50%, relative to vehicle. However, scopoletin (1) exhibited no effect on the phagocytosis or survival of BM-iDCs in vitro. 相似文献
86.
Wenling Li Christian Köhler Prof. Zhi Yang Prof. Dietmar Stalke Dr. Regine Herbst-Irmer Prof. Herbert W. Roesky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(5):1193-1197
Lewis base cAACs stabilized monomeric silylenes with halogen or methyl substituents at the silicon center have not been reported due to the strong σ-donor and π-acceptor character of cAAC. To prepare these monomeric silylenes, we used the silicon(IV) precursors 5 and 6 with a nitrogen donor group L (L=o-C6H4NMe2). The cAAC-stabilized (cAAC=C(CH2)(CMe2)2N-Ar, Ar=2,6-iPr2C6H3) silylenes LSiCl(cAAC) ( 7 ) and LSiMe(cAAC) ( 8 ) were synthesized by reduction of LSiCl3 and LSiMeCl2 with two equivalents of KC8 in the presence of one equivalent of cAAC, respectively. Compounds 7 and 8 were characterized by single-crystal X-ray crystallography, NMR spectroscopy, and elemental analysis. Compounds 7 and 8 are stable in the solid state as well as in solution at room temperature for at least four months under inert conditions. 相似文献
87.
本文报道了21种氨基酸的七氟丁酰异丁酯的毛细管气相色谱分析方法;优选了衍生反应条件;建立了风化煤中氨基酸的分离、定量分析方法;经16种样品测定,均获得满意的结果。 相似文献
88.
FeCl3·6H2O-promoted biomimetic oxidations of 3,5-dihalogeno-resveratrol in different acetone systems produced several coupling intermediates bearing distinct dimeric skeletons with moderate yields. The subsequent deprotection reactions of brominated coupling products achieved the efficient synthesis of natural products (±)-ε-viniferin, (±)-ampelosin B, and (±)-gnetins F, as well as an unnatural oligostilbene. The coupling mechanisms for the formation of different dimeric structures were also proposed. 相似文献
89.
Wenling Li Tao Dong Peilan Chen Xiaolin Liu Meijie Liu Xiaoqian Han 《Tetrahedron》2017,73(21):3056-3065
The simple synthesis of (±)-parthenostilbenins A and B and (±)-quadrangularins A and B, as well as several unnatural resveratrol dimers, was successfully accomplished for the first time. Moreover, (±)-restrytisols B, (±)-leachianols F and G were efficiently prepared with higher yields compared with those in the literatures. The regioselective oxidative coupling reactions of 3,5-dibromo-resveratrol catalyzed by different enzymes in various solvent systems were used as key steps. The coupling mechanisms for the formation of distinct dimeric skeletons were also proposed. 相似文献
90.
将经典风险模型推广为带干扰的双Cox风险模型,使该模型更符合现实情况,然后利用鞅论的知识对其进行研究,得到了该模型的破产概率的Lundberg指数上界,并讨论了当c=0时,该模型的非Lundberg指数上界. 相似文献