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21.
Shoko Hoshina Kei Yura Honami Teranishi Noriko Kiyasu Ayumi Tominaga Haruka Kadoma Ayaka Nakatsuka Tomoko Kunichika Chikashi Obuse Shou Waga 《The Journal of biological chemistry》2013,288(42):30161-30171
Origin recognition complex (ORC), consisting of six subunits ORC1–6, is known to bind to replication origins and function in the initiation of DNA replication in eukaryotic cells. In contrast to the fact that Saccharomyces cerevisiae ORC recognizes the replication origin in a sequence-specific manner, metazoan ORC has not exhibited strict sequence-specificity for DNA binding. Here we report that human ORC binds preferentially to G-quadruplex (G4)-preferable G-rich RNA or single-stranded DNA (ssDNA). We mapped the G-rich RNA-binding domain in the ORC1 subunit, in a region adjacent to its ATPase domain. This domain itself has an ability to preferentially recognize G4-preferable sequences of ssDNA. Furthermore, we found, by structure modeling, that the G-rich RNA-binding domain is similar to the N-terminal portion of AdoMet_MTase domain of mammalian DNA methyltransferase 1. Therefore, in contrast with the binding to double-stranded DNA, human ORC has an apparent sequence preference with respect to its RNA/ssDNA binding. Interestingly, this specificity coincides with the common signature present in most of the human replication origins. We expect that our findings provide new insights into the regulations of function and chromatin binding of metazoan ORCs. 相似文献
22.
Yasuhide Ota Teruaki Nakamiya Koichi Yamada 《Bioscience, biotechnology, and biochemistry》2013,77(9):1368-1374
The lipase from Candida paralipolytica was purified, as judged by disc electrophoresis. The purification was about 132 fold, based on protein, with a recovery of 32% from the acetone precipitate of the cultivated broth.After purification, modification of the enzyme was performed by dialyzing its solution against 1 m sodium chloride in acetate buffer at room temperature and by separating the modified enzyme from an unknown substance(s) with a Sephadex G–75 column.The optimum pH for lipolysis of the purified lipase was 8.0, while that of the modified one was 7.0. Sodium taurocholate was required essentially by the purified enzyme, but not by the modified one. The purified lipase was stable below 37°C and in the pH range from 3.5 to 9.0 at 5°C. 相似文献
23.
Satoru Tamura Kunichika Yoshihira Katsuaki Fujiwara Nobutoshi Murakami 《Bioorganic & medicinal chemistry letters》2010,20(7):2299-2302
Exploration for inhibitors against expression of IgE receptor (FcεRI) on human mast cell, a significant trigger to acute and chronic allergic symptoms, disclosed epigallocatechin gallate (EGCG), epicatechin gallate, and gallocatechin gallate as active principles. Additionally, the anthocyanidin, delphinidin, and the flavone, tricetinidin, possessing a pyrogallol function were also revealed to suppress expression of FcεRI. Structure–activity relationship analysis among catechins, anthocyanidins, and flavones revealed the pyrogallol moiety to be crucial for biological potency. Furthermore, EGCG was clarified to reduce generation of γ-chain subunit to suppress expression of FcεRI on human mast cells. 相似文献
24.
Apolipoprotein B (apoB) is known to be a ferritin-binding protein. Here we show that apoB binds to ferritin through hemin-mediated
binding. Human apoB bound to bovine spleen, horse spleen, and canine liver ferritins, but did not bind to bovine apoferritin,
even after incorporation of iron into it. Incubation of apoferritin with hemin resulted in apoB binding with apoferritin at
the same level as with holoferritin. In contrast, hemin inhibited binding of apoB to ferritin. Bovine spleen apoferritin bound
biotinylated hemin, and hemin inhibited the binding between the apoferritin and biotinylated hemin, suggesting that ferritin
binds hemin directly. ApoB and LDL containing apoB bound biotinylated hemin, and their bindings were also inhibited by hemin,
but not protoporphyrin IX. These data demonstrate that binding of apoB to ferritin is mediated through ferritin’s binding
to hemin, and also that apoB binds hemin directly. 相似文献
25.
Synchronization has been observed in various systems, including living beings. In a previous study, we reported a new phenomenon with antisynchronization in calling behavior of two interacting Japanese tree frogs. In this paper, we theoretically analyse nonlinear dynamics in a system of three coupled oscillators, which models three interacting frogs, where the oscillators of each pair have the property of antisynchronization; in particular, we perform bifurcation analysis and Lyapunov function analysis. 相似文献
26.
We investigated the robustness of hen lysozyme by using random mutant libraries. Six random mutant libraries containing 1, 1.5, 2, 3, 5 and 14 amino acid mutations per hen lysozyme were systematically constructed by varying the concentrations of Mg(2+) and Mn(2+) on polymerase chain reaction. The mutated genes from the six libraries were cloned to a yeast expression vector and a total of 4000 clones were screened on the basis of lysis activity and ELISA employing monoclonal antibody that recognized only lysozyme with native conformation. About 80% of the clones with an average of two amino acid mutations retained active structure. Almost all clones with an average of five mutations lost active structure. On the other hand, 80% of the clones with an average of two amino acid mutations retained both gross conformation and active structure and 24% of the clones with an average of 14 amino acid mutations retained gross conformation. These results show that gross conformation is robust against mutations and so is active structure to a lesser extent. 相似文献