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41.
Localization and verification by synthesis of five antigenic sites of bovine serum albumin. 总被引:1,自引:0,他引:1 下载免费PDF全文
Recently we have shown that the major antigenic sites of bovine serum albumin exhibit functional equivalence progessively increasing with the time at which antibodies are obtained after the first immunization. Analysis of our recent immunochemical findings and the known covalent structure of bovine serum albumin have enabled us to predict the locations of five antigenic sites of bovine serum albumin. The predicted locations were synthesized, and immunochemical studies with late-course antisera showed them to constitute antigenic sites of native bovine serum albumin. 相似文献
42.
Alan D. Fleming Ryuzo Yanagimachi Hiroko Yanagimachi 《Molecular reproduction and development》1979,2(4):357-366
Mature unfertilized ova from superovulated hamsters were freed from all investments and frozen at ?50°C. They were cooled at about 1°C/min to 0°C then at 0.8° to 0.6°C/min to ?50°C. At 0°C, dimethyl sulfoxide was added to a final concentration of 1.25 M. The ova were stored at ?50°C for up to four months. Thawing was performed at 2–4°C/min and followed by several washes with insemination medium. Approximately 90% of the ova were normal in appearance after thawing. The frozen and thawed ova with normal appearance could be penetrated by hamster or human spermatozoa at a rate comparable to unfrozen controls. The ability of hamster ova to tolerate storage at a relatively convenient temperature (?50°C) for long periods (tested for up to four months) makes possible their shipment at low cost to institutions lacking this resource. There they can be used for basic biological studies of sperm–egg interaction or in the clinical assessment of human sperm quality. 相似文献
43.
T Erabi T Higuti K Sakata T Kakuno J Yamashita M Tanaka T Horio 《Journal of biochemistry》1976,79(3):497-503
Polarographic studies on oxidation-reduction components bound with chromatophores from Rhodospirillum rubrum were carried out at 24 degrees. 1. Using a carbon-paste electrode as the working electrode, polarographic waves characteristic of oxidation-reduction components were observed in the presence, but not in the absence of Triton X-100; these waves were therefore measured in the presence of the detergent. 2. At least two kinds of oxidation-reduction components were detectable, having different half-wave potentials (E1/2); at pH 7, one had an E1/2 value of +275 mV (POC+275) and the other had a value of +60 mV (POC+60). 3. POC+275 was reduced by succinate and by NADH. Both reductions were almost completely inhibited by antimycin A, which hardly affected the reductions of ubiquinone-10 by succinate and by NADH. Most POC+275 molecules were not reduced by the substrates when quinones were extracted from the chromatophores, and the reductions were mostly restored when ubiquinone-10 was re-added. This indicates that POC+275 is functional between ubiquinone-10 and cytochrome c2 in the electron transport system. 4. POC+60 was reduced by succinate, but hardly at all by NADH. The reduction of POC+60 was not influenced either by the addition of antimycin A or by the extraction of quinones. This suggests that POC+60 is functional in the process from succinate dehydrogenase [EC 1.3.99.1] to ubiquinone-10 in the electron transport system. 5. Of the POC+275 reducible by dithionite, approximately 70% could be reduced in the absence of Triton X-100, provided that the potential of the working electrode immersed in chromatophore suspensions was set at potentials of 0 mV or lower and that the electrochemical reaction was carried out at pH 7.5. When the potential of the electrode was set at +50 mV (the same as the E1/2 value of ubiquinone-10 bound with chromatophores), and the suspension was allowed to stand for various lengths in the presence of the detergent, it was found that approximately half of the electrochemically reducible POC+275 was rapidly reduced, followed by a slow reduction. The discrepancy in the oxidation-reduction equilibrium on the basis of the E1/2 values of ubiquinone-10 and POC+275 is discussed. 相似文献
44.
Shohei Katsuta Goro Masuda Hyeokjin Bak Akihisa Shinozawa Yoshiaki Kamiyama Taishi Umezawa Daisuke Takezawa Izumi Yotsui Teruaki Taji Yoichi Sakata 《The Plant journal : for cell and molecular biology》2020,103(2):634-644
Given their sessile nature, land plants must use various mechanisms to manage dehydration under water‐deficit conditions. Osmostress‐induced activation of the SNF1‐related protein kinase 2 (SnRK2) family elicits physiological responses such as stomatal closure to protect plants during drought conditions. With the plant hormone ABA receptors [PYR (pyrabactin resistance)/PYL (pyrabactin resistance‐like)/RCAR (regulatory component of ABA receptors) proteins] and group A protein phosphatases, subclass III SnRK2 also constitutes a core signaling module for ABA, and osmostress triggers ABA accumulation. How SnRK2 is activated through ABA has been clarified, although its activation through osmostress remains unclear. Here, we show that Arabidopsis ABA and abiotic stress‐responsive Raf‐like kinases (AtARKs) of the B3 clade of the mitogen‐activated kinase kinase kinase (MAPKKK) family are crucial in SnRK2‐mediated osmostress responses. Disruption of AtARKs in Arabidopsis results in increased water loss from detached leaves because of impaired stomatal closure in response to osmostress. Our findings obtained in vitro and in planta have shown that AtARKs interact physically with SRK2E, a core factor for stomatal closure in response to drought. Furthermore, we show that AtARK phosphorylates S171 and S175 in the activation loop of SRK2E in vitro and that Atark mutants have defects in osmostress‐induced subclass III SnRK2 activity. Our findings identify a specific type of B3‐MAPKKKs as upstream kinases of subclass III SnRK2 in Arabidopsis. Taken together with earlier reports that ARK is an upstream kinase of SnRK2 in moss, an existing member of a basal land plant lineage, we propose that ARK/SnRK2 module is evolutionarily conserved across 400 million years of land plant evolution for conferring protection against drought. 相似文献
45.
Fujishiro Miyuki Yahagi Shoichi Takemi Shota Nakahara Mio Sakai Takafumi Sakata Ichiro 《Molecular biology reports》2021,48(7):5513-5518
Molecular Biology Reports - Pyridoxine (PN), one of the vitamers of vitamin B6, plays an important role in the maintenance of epidermal function and is used to treat acne and rough skin. Clinical... 相似文献
46.
47.
Yuriko Yamagat Ken-ichi Tomita Nobuhiro Marubayashi Ikuhiko Ueda Shinji Sakata Akira Matsuda 《Nucleosides, nucleotides & nucleic acids》2013,32(2-4):835-853
Abstract 2′-Deoxy-2′-methylidenecytidine (DMDC), a potent inhibitor of the growth of tumor cells, was crystallized with two different forms. One is dihydrated (DMDC·2H2O) and the other is its hydrochloride salt (DMDC·HCLl). Both crystal and molecular structures have been determined by the X-ray diffraction method. In both forms the glycosidic and sugar conformations are anti and C(4′)-exo, respectively, whereas the conformation about the exocyclic bond is trans for DMDC·2H2O and gauche + for DMDC·HCl. Proton nuclear magnetic resonance data of DMDC indicate a preference for the anti C(4′)-exo conformation found in the solid state. These molecular conformations were compared with the related pyrimidine nucleosides. When the cytosine bases are brought into coincidence, DMDC displays the exocyclic C(4′)-C(5′) bond located on the very close position to those of pyrimidine nucleosides with typical overall conformations. On the other hand, the hydroxyl O(3′)-H groups are separated by ca. 3 Å in the cases of DMDC and other pyrimidine nucleosides which have the C(2′)-endo sugar conformation. This result may be useful for the implication about the mechanism of the biological activity of DMDC. 相似文献
48.
Motoyuki Nakamura Yorihiko Koeda Fumitaka Tanaka Toshiyuki Onoda Kazuyoshi Itai Masaki Ohsawa Kozo Tanno Kiyomi Sakata Shinich Omama Yasuhiro Ishibashi Shinji Makita Mutsuko Ohta Kuniaki Ogasawara Takashi Komatsu Akira Okayama 《PloS one》2013,8(12)
Objectives
Atrial fibrillation (AF) is a significant public health issue due to its high prevalence in the general population, and is associated with an increased risk of cardiovascular (CV) events including systemic thrombo-embolism, heart failure, and coronary artery disease. The relationship between plasma B-type natriuretic peptide (BNP) and CV risk in real world AF subjects remains unknown.Methods
The subject of the study (n = 228; mean age = 69 years) was unselected individuals with AF in a community-based population (n = 15,394; AF prevalence rate = 1.5%). The CV event free rate within each BNP tertile was estimated, and Cox regression analysis was performed to examine the relative risk of the onset of CV events among the tertiles. The prognostic ability of BNP was compared to an established risk score for embolic events (CHADS2 score). In addition, to determine the usefulness of BNP as a predictor in addition to CHADS2 score, we calculated Net Reclassification Improvement (NRI) and Integrated Discrimination Improvement (IDI) indices.Results
During the follow-up period 58 subjects experienced CV events (52 per 1,000 person-years). The event-free ratio was significantly lower in the highest tertile (p < 0.02). After adjustment for established CV risk factors, the hazard ratio (HR) of the highest tertile was significantly higher than that of the lowest tertile (HR = 2.38; p < 0.02). The predictive abilities of plasma BNP in terms of sensitivity and specificity for general CV events were comparable to those of CHADS2 score. Adding BNP to the CHADS2 score only model improved the NRI (0.319; p < 0.05) and the IDI (0.046; p < 0.05).Conclusion
Plasma BNP is a valuable biomarker both singly or in combination with an established scoring system for assessing general CV risk including stroke, heart failure and acute coronary syndrome in real-world AF subjects. 相似文献49.
Plaque ruptures in atherosclerotic carotid arteries cause cerebral strokes. Accumulation of lipoproteins in the deep intimal layer forms a lipid core (LC), whose progression may be enhanced by mechanical conditions on the arterial wall. In this study, we investigated the pressure conditions of a liquid LC through numerical simulations of a sliced segment finite element (FE) model and a three-dimensional (3D) symmetric FE model. A model of an LC filled with nearly incompressible fluid was compared with incompressible and soft neo-Hookean LC models in a static FE analysis. Material constants for a nonlinear hyperelastic model of the arterial wall were identified based on an inflation test using a tube specimen. The results from the FE analysis of a sliced segment model show an LC fluid pressure as low as 1.9 kPa at a blood pressure of 16 kPa. A neo-Hookean LC model with a Young’s modulus of 0.06 kPa produced an almost uniform pressure in the LC within an error of 1.3 %. The 3D model predicted a similar level of LC pressure. Such low fluid pressure in the LC region may enhance the infiltration of lipoproteins and other substances from the lumen and facilitate transport through microvessels from the adventitia to the LC. 相似文献
50.
Mitsuhide Hamaguchi Hironari Kamikubo Kayo N. Suzuki Yoshihisa Hagihara Itaru Yanagihara Ikuhiro Sakata Mikio Kataoka Daizo Hamada 《PloS one》2013,8(8)
Enterohaemorrhagic E. coli (EHEC) induces actin reorganization of host cells by injecting various effectors into host cytosol through type III secretion systems. EspB is the natively partially folded EHEC effector which binds to host α-catenin to promote the actin bundling. However, its structural basis is poorly understood. Here, we characterize the overall structural properties of EspB based on low-resolution structural data in conjunction with protein dissection strategy. EspB showed a unique thermal response involving cold denaturation in the presence of denaturant according to far-UV circular dichroism (CD). Small angle X-ray scattering revealed the formation of a highly extended structure of EspB comparable to the ideal random coil. Various disorder predictions as well as CD spectra of EspB fragments identified the presence of α-helical structures around G41 to Q70. The fragment corresponding to this region indicated the thermal response similar to EspB. Moreover, this fragment showed a high affinity to C-terminal vinculin homology domain of α-catenin. The results clarified the importance of preformed α-helix of EspB for recognition of α-catenin. 相似文献