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81.
Algal nutrient studies in chemically-defined media typically employ a synthetic chelator to prevent iron hydroxide precipitation. Micronutrient-particulate interactions may, however, significantly affect chemical speciation and hence biovailability of these nutrients in natural waters. A technique is described by which Selenastrum capricornutum Printz (Chlorophyta) may be cultured in a medium where trace metal speciation (except iron) is controlled, not by organic chelation, but by sorption onto titanium dioxide. Application of this culturing protocol in conjunction with results from sorption studies of nutrient ions on mineral particles provides a means of studying biological impacts of sorptive processes in aquatic environments. 相似文献
82.
83.
S. Kuwabara 《The Biochemical journal》1970,118(3):457-465
1. When Bacillus cereus 569/H was grown in a casamino acid (casein-hydrolysate) medium containing zinc sulphate rapid production of extracellular beta-lactamase II preceded that of beta-lactamase I. 2. beta-Lactamase I was separated from beta-lactamase II by fractional precipitation with ammonium sulphate. 3. beta-Lactamase I was purified by a process involving chromatography on Celite and DEAE-cellulose and beta-lactamase II by chromatography on DEAE-cellulose after denaturation of beta-lactamase I by heat. Both enzymes were obtained in crystalline form. 4. beta-Lactamase II prepared in this way appeared to have a higher molecular weight than beta-lactamase I and required Zn(2+) as a cofactor for both cephalosporinase and penicillinase activities. 相似文献
84.
85.
Yagi M Narita K Maruyama S Sone K Kuwabara T Shimizu K 《Biochimica et biophysica acta》2007,1767(6):660-665
Adsorption of [(OH(2))(terpy)Mn(mu-O)(2)Mn(terpy)(OH(2))](3+) (terpy=2,2':6',2"-terpyridine) (1) onto montmorillonite K10 (MK10) yielded catalytic dioxygen (O(2)) evolution from water using a Ce(IV) oxidant. The Mn K-edge X-ray absorption near edge structure (XANES) of the 1/MK10 hybrid suggested that the oxidation state of the di-mu-oxo Mn(2) core could be Mn(III)-Mn(IV). However the pre-edge peak in the XANES spectrum of 1 adsorbed on MK10 is different from the neat 1 powder. The kinetic analysis of O(2) evolution showed that the catalysis requires cooperation of two equivalents of 1 adsorbed on MK10. The reaction of the [(bpy)(2)Mn(mu-O)(2)Mn(bpy)(2)](3+) (bpy=2,2'-bipyridine) (2)/MK10 hybrid with a Ce(IV) oxidant evolved O(2). However, the turnover number value was less than unity for 2/MK10, showing that 2 adsorbed on MK10 does not work as a catalyst. The terminal water ligands could be an important for the catalysis by adsorbed 1. The mechanism of O(2) production by photosynthetic oxygen evolving complex is discussed based on catalytic O(2) evolution by 1 adsorbed on MK10. 相似文献
86.
T Wada Y Yoshikawa S Tokuyama M Kuwabara H Akita T Miyagi 《Biochemical and biophysical research communications》1999,261(1):21-27
Here we report the cDNA sequence of a human ganglioside sialidase. The cDNA was isolated from a human brain cDNA library by screening with a 240 bp probe generated by polymerase chain reaction using primers based on the sequences of rat cytosolic and bovine membrane sialidases which we previously cloned. The 3.0 kb cDNA encodes an open reading frame of 436 amino acids containing a putative transmenbrane domain and an Arg-Ile-Pro and three Asp-box sequences characteristic of sialidases and showing overall 83% and 39% identities to the bovine and rat enzymes, respectively. Northern blot analysis revealed high expression in skeletal muscle and testis, but low level in kidney, placenta, lung, and digestive organs. Transient expression of the cDNA in COS-1 cells resulted in a 130-fold increase in sialidase activity compared to the control level, and the activity was found to be almost specific for gangliosides. Fluorescent in situ hybridization allowed the human sialidase gene localized to chromosome 11 at q 13.5. 相似文献
87.
88.
Yutaka Horiuchi Makiko Tominaga Mika Ichikawa Masao Yamashita Yuri Jikumaru Yoko Nariai Yuko Nakajima Masato Kuwabara Masayoshi Yukawa 《Microbiology and immunology》2009,53(8):468-474
It is well known that lymphocytes from patients with advanced-stage cancer have impaired immune responsiveness and that type1 T lymphocyte subsets in tumor bearing hosts are suppressed. Treg have been reported to comprise a subgroup which inhibits T cell mediated immune responses. In the present study, the percentage of Treg, Th1 and Tc1 in the peripheral blood of tumor bearing dogs with or without metastases was evaluated. The percentages of Th1 and Tc1 in dogs with metastatic tumor were significantly less, and that of Treg was significantly greater, than those of dogs without metastatic tumor. The percentage of Treg showed an inverse correlation with that of Th1 and Tc1 in tumor bearing dogs. It was concluded that an increase in Treg in the peripheral blood of dogs with metastatic tumor may induce suppression of tumor surveillance by the Type1 immune response and lead to metastasis of tumor[0][0].[0] 相似文献
89.
Prolyl 4-Hydroxylation of ��-Fibrinogen: A NOVEL PROTEIN MODIFICATION REVEALED BY PLASMA PROTEOMICS*
Masaya Ono Junichi Matsubara Kazufumi Honda Tomohiro Sakuma Tomoyo Hashiguchi Hiroshi Nose Shoji Nakamori Takuji Okusaka Tomoo Kosuge Naohiro Sata Hideo Nagai Tatsuya Ioka Sachiko Tanaka Akihiko Tsuchida Tatsuya Aoki Masashi Shimahara Yohichi Yasunami Takao Itoi Fuminori Moriyasu Ayako Negishi Hideya Kuwabara Ayako Shoji Setsuo Hirohashi Tesshi Yamada 《The Journal of biological chemistry》2009,284(42):29041-29049
Plasma proteome analysis requires sufficient power to compare numerous samples and detect changes in protein modification, because the protein content of human samples varies significantly among individuals, and many plasma proteins undergo changes in the bloodstream. A label-free proteomics platform developed in our laboratory, termed “Two-Dimensional Image Converted Analysis of Liquid chromatography and mass spectrometry (2DICAL),” is capable of these tasks. Here, we describe successful detection of novel prolyl hydroxylation of α-fibrinogen using 2DICAL, based on comparison of plasma samples of 38 pancreatic cancer patients and 39 healthy subjects. Using a newly generated monoclonal antibody 11A5, we confirmed the increase in prolyl-hydroxylated α-fibrinogen plasma levels and identified prolyl 4-hydroxylase A1 as a key enzyme for the modification. Competitive enzyme-linked immunosorbent assay of 685 blood samples revealed dynamic changes in prolyl-hydroxylated α-fibrinogen plasma level depending on clinical status. Prolyl-hydroxylated α-fibrinogen is presumably controlled by multiple biological mechanisms, which remain to be clarified in future studies.For comprehensive analysis of plasma proteins, it is necessary to compare a sufficient number of blood samples to avoid simple interindividual heterogeneity, because the protein content of human samples varies significantly among individuals. Also, the provision of sufficient power is needed to detect protein modification because many plasma proteins undergo changes in the bloodstream (1). Even though the proteomic technologies have advanced (2, 3), there remains room for improvement. Different isotope labeling and identification-based methods have been developed for quantitative proteomics technologies (4–6), but the number of samples that can be compared by the current isotope-labeling methods is limited, and identification-based proteomics is unable to capture information regarding unknown modifications.A label-free proteomics platform developed in our laboratory, termed “Two-Dimensional Image Converted Analysis of Liquid chromatography and mass spectrometry (2DICAL)2 (7), simply compares the liquid chromatography and mass spectrometry (LC-MS) data and detects a protein modification by finding changes in the mass to charge ratio (m/z) and retention time (RT). Enhanced methods for accurate MS peak alignment across multiple LC runs have enabled the successful implementation of clinical studies requiring comparison of a large number of samples (8, 9). Using 2DICAL to analyze plasma samples of pancreatic cancer patients and healthy controls, novel prolyl hydroxylation of α-fibrinogen was successfully discovered.Fibrinogen and its modification has been investigated because of its clinical importance (10, 11). On the other hand, prolyl hydroxylation has attracted attention after the discovery of the hypoxia-inducible factor 1α (HIF1α) prolyl-hydroxylase and its role in switching of HIF1α functions (12). Prolyl hydroxylation in other proteins has been energetically sought, but only a few such proteins have been identified (13). Only one study has reported prolyl hydroxylation of fibrinogen at the β chain (14).Here, we report the detection of prolyl 4-hydroxylated α-fibrinogen by plasma proteome analysis, a protein modification that dynamically changes in plasma depending on the clinical status and is a candidate plasma biomarker. 相似文献
90.
Louise H. Fornander Axelle Renodon-Cornière Naoyuki Kuwabara Kentaro Ito Yasuhiro Tsutsui Toshiyuki Shimizu Hiroshi Iwasaki Bengt Nordén Masayuki Takahashi 《Nucleic acids research》2014,42(4):2358-2365
The Swi5-Sfr1 heterodimer protein stimulates the Rad51-promoted DNA strand exchange reaction, a crucial step in homologous recombination. To clarify how this accessory protein acts on the strand exchange reaction, we have analyzed how the structure of the primary reaction intermediate, the Rad51/single-stranded DNA (ssDNA) complex filament formed in the presence of ATP, is affected by Swi5-Sfr1. Using flow linear dichroism spectroscopy, we observe that the nucleobases of the ssDNA are more perpendicularly aligned to the filament axis in the presence of Swi5-Sfr1, whereas the bases are more randomly oriented in the absence of Swi5-Sfr1. When using a modified version of the natural protein where the N-terminal part of Sfr1 is deleted, which has no affinity for DNA but maintained ability to stimulate the strand exchange reaction, we still observe the improved perpendicular DNA base orientation. This indicates that Swi5-Sfr1 exerts its activating effect through interaction with the Rad51 filament mainly and not with the DNA. We propose that the role of a coplanar alignment of nucleobases induced by Swi5-Sfr1 in the presynaptic Rad51/ssDNA complex is to facilitate the critical matching with an invading double-stranded DNA, hence stimulating the strand exchange reaction. 相似文献