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961.
962.
Angelina A. Parkhomchuk Nina A. Kocharova Alexander S. Shashkov Yuriy A. Knirel 《Carbohydrate research》2010,345(9):1235-1239
The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Providencia alcalifaciens O12. Its structure was studied by sugar analysis using GLC of the alditol acetates and (S)-2-octyl glycosides, methylation analysis, Smith degradation, and 1H and 13C NMR spectroscopy, including 2D 1H-1H COSY, TOCSY, ROESY, 1H-13C HSQC, and HMBC experiments. It was found that the polymer is a neutral heteropolysaccharide and has a branched heptasaccharide repeating unit with the following structure: 相似文献
963.
964.
Inga-Lill Mårtensson Nina Almqvist Ola Grimsholm Angelina I. Bernardi 《FEBS letters》2010,584(12):2572-141
B lymphocytes are essential antibody-producing cells of the immune system. During the development of progenitor B cells to mature B cells that express a membrane-bound antibody, the B cell receptor (BCR), the cells undergo selection at several checkpoints, which ensures that a diverse antibody repertoire is generated and that the BCRs recognise foreign-, but not self-, antigens. In this review, we consider the pre-BCR checkpoint. Mutations or alterations that affect this checkpoint underpin the development of pre-B cell leukemias, primary immunodeficiency, and possibly, systemic autoimmunity. 相似文献
965.
966.
Doris Ribitsch Sonja Winkler Karl Gruber Wolfgang Karl Eva Wehrschütz-Sigl Inge Eiteljörg Petra Schratl Peter Remler Regina Stehr Cornelius Bessler Nina Mußmann Kerstin Sauter Karl Heinz Maurer Helmut Schwab 《Applied microbiology and biotechnology》2010,87(5):1743-1752
In order to engineer the choline oxidase from Arthrobacter nicotianae (An_CodA) for the potential application as biological bleach in detergents, the specific activity of the enzyme toward the synthetic substrate tris-(2-hydroxyethyl)-methylammonium methylsulfate (MTEA) was improved by methods of directed evolution and rational design. The best mutants (up to 520% wt-activity with MTEA) revealed mutations in the FAD- (A21V, G62D, I69V) and substrate-binding site (S348L, V349L, F351Y). In a separate screening of a library comprising of randomly mutagenised An_CodA, with the natural substrate choline, four mutations were identified, which were further combined in one clone. The constructed clone showed improved activity towards both substrates, MTEA and choline. Mapping these mutation sites onto the structural model of An_CodA revealed that Phe351 is positioned right in the active site of An_CodA and very likely interacts with the bound substrate. Ala21 is part of an α-helix which interacts with the diphosphate moiety of the flavin cofactor and might influence the activity and specificity of the enzyme. 相似文献
967.
968.
Wolbachia属共生菌的侵染是引起跳虫——白符虫兆孤雌生殖的原因。对带有正常沃尔巴克氏体菌群的白符虫兆卵和通过利福平处理剔除沃尔巴克氏体菌群的白符虫兆卵的胚胎发育进行实验观察。白符虫兆的活性卵产出3到4天后,卵体大小显著性地增大,并伴随卵体形状从球形到圆饼形的变化。这些变化在利福平处理的或者是7%自然失活的非活性卵中都没有出现。推测沃尔巴克氏体在白符虫兆卵产出后的3天之内或者3天之前的受精卵发育或胚胎发育中发挥着重要作用;同时根据目前已有的研究结果推断沃尔巴克氏体对白符虫兆卵发育可能的影响机制。 相似文献
969.
Anna Di Fiore Emanuela Truppo Claudiu T. Supuran Vincenzo Alterio Nina Dathan Fatemeh Bootorabi Seppo Parkkila Simona Maria Monti Giuseppina De Simone 《Bioorganic & medicinal chemistry letters》2010,20(17):5023-5026
Human carbonic anhydrase VII (hCA VII) is a cytosolic member of the α-CA family. This enzyme is mainly localized in a number of brain tissues such as the cortex, hippocampus and thalamus and has been noted for its contribution in generating neuronal excitation and seizures. Recently, it has been also proposed that hCA VII may be involved in the control of neuropathic pain, thus its inhibition may offer a new approach in designing pain killers useful for combating neuropathic pain. We report here the X-ray crystallographic structure of a mutated form of human CA VII in complex with acetazolamide, a classical sulfonamide inhibitor. These crystallographic studies provide important implications for the rational drug design of selective CA inhibitors with clinical applications. 相似文献
970.