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291.
Kazutaka Hirakawa Norihito Fukunaga Yoshinobu Nishimura Tatsuo Arai Shigetoshi Okazaki 《Bioorganic & medicinal chemistry letters》2013,23(9):2704-2707
For the purpose of the basic study of photodynamic therapy, the activity of the water-soluble P(V)porphyrin, dimethoxyP(V)tetraphenylporphyrin chloride (DMP(V)TPP), on photosensitized protein damage was examined. The quantum yield of singlet oxygen generation by DMP(V)TPP (0.64) was comparable with that of typical porphyrin photosensitizers. Absorption spectrum measurement demonstrated the binding interaction between DMP(V)TPP and human serum albumin, a water-soluble protein. Photo-irradiated DMP(V)TPP damaged the amino acid residue of human serum albumin, resulting in the decrease of the fluorescence intensity from the tryptophan residue of human serum albumin. A singlet oxygen quencher, sodium azide, could not completely inhibit the damage of human serum albumin, suggesting that the electron transfer mechanism contributes to protein damage as does singlet oxygen generation. The decrease of the fluorescence lifetime of DMP(V)TPP by human serum albumin supported the electron transfer mechanism. The estimated contribution of the electron transfer mechanism is 0.64. These results suggest that the activity of DMP(V)TPP can be preserved under lower oxygen concentration condition such as tumor. 相似文献
292.
Tamotsu Hirakawa Tsutomu Tanaka Kiyoshi Watanabe 《Bioscience, biotechnology, and biochemistry》2013,77(1):123-130
Methionine auxotrophs were derived by the treatment with ultraviolet ray or N-methylN′-nitro-N-nitrosoguanidine from five strains of Escherichia coli. One of the methionine auxotrophs of E. coli C-6, strain No. 15, produced maximum amount of l-threonine (4.3 mg/ml) with the medium containing 5 % cane-molasses (as sugars). Double auxotrophs were derived with further mutational treatment from strain No. 15. It was found that l-threonine production was greatly enhanced by cultivating methionine-valine auxotrophs in the presence of l-valine and methionine. o.ne of the methionine-valine auxotroph, strain No. 234, produced maximum amount of l-threonine (10.5 mg/ml) from cane-molasses.The requirement of l-valine for the growth of the strain No. 234 was found to be leaky, and it was suggested that some enzymes relating to l-valine metabolism were mutationally altered to temperature-sensitive. 相似文献
293.
Hideki Hirakawa Kenta Shirasawa Akio Ohyama Hiroyuki Fukuoka Koh Aoki Christophe Rothan Shusei Sato Sachiko Isobe Satoshi Tabata 《DNA research》2013,20(3):221-233
The genotype data of 7054 single nucleotide polymorphism (SNP) loci in 40 tomato lines, including inbred lines, F1 hybrids, and wild relatives, were collected using Illumina''s Infinium and GoldenGate assay platforms, the latter of which was utilized in our previous study. The dendrogram based on the genotype data corresponded well to the breeding types of tomato and wild relatives. The SNPs were classified into six categories according to their positions in the genes predicted on the tomato genome sequence. The genes with SNPs were annotated by homology searches against the nucleotide and protein databases, as well as by domain searches, and they were classified into the functional categories defined by the NCBI''s eukaryotic orthologous groups (KOG). To infer the SNPs'' effects on the gene functions, the three-dimensional structures of the 843 proteins that were encoded by the genes with SNPs causing missense mutations were constructed by homology modelling, and 200 of these proteins were considered to carry non-synonymous amino acid substitutions in the predicted functional sites. The SNP information obtained in this study is available at the Kazusa Tomato Genomics Database (http://plant1.kazusa.or.jp/tomato/). 相似文献
294.
Amer Ali Abd El-Hafeez Takashi Fujimura Rikiya Kamei Noriko Hirakawa Kenji Baba Kazuhisa Ono Seiji Kawamoto 《Cytotechnology》2018,70(3):913-919
Anti-cancer tyrosine kinase inhibitors (TKIs) are effective in many types of cancers including non-small cell lung cancer, while appearance of TKI-resistant tumors suggests a need for the development of their potentiation strategies. We have previously shown that a methoxyflavanone derivative from the Asian medicinal herb Perilla frutescens (Perilla-derived methoxyflavanone; PDMF) shows a prominent anti-tumor activity against A549 human lung adenocarcinoma. Here we show that PDMF and anti-cancer TKIs (nilotinib, bosutinib, dasatinib, and ponatinib) synergistically suppress proliferation of A549 cells. Flow cytometric analysis indicated that co-stimulation with nilotinib (4 μM) and PDMF induced G2/M cell cycle arrest in low PDMF doses (10–50 μM), whereas this combination triggered de novo G1 arrest in higher PDMF dosages (50–125 μM). We also found that co-administration with nilotinib and PDMF significantly suppressed in vivo tumorigenicity of A549 cells in athymic nude mice. 相似文献
295.
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297.
Sawada H Yamahama Y Mase K Hirakawa H Iino T 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2007,146(2):172-179
We previously reported the purification of an ommin-binding protein (OMBP) from an acid-methanol extract of diapause eggs of the silkworm and that OMBP reacted with the anti-30K proteins antiserum. In order to clarify the relationship between OMBP and the 30K proteins, we attempted to determine the sequence of the N-terminal amino acid of OMBP, which was separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). We observed ten protein spots of various isoelectric points; the spots corresponded with 30 kDa. Based on the sequence of the N-terminal amino acid (20 residues), the spots belonged to two kinds of 30K proteins (6G1 and 19G1), which are known as the major plasma proteins in the larval hemolymph of the silkworm. The proteins are expected to attach to polysaccharide because they reacted with concanavalin A and elderberry bark lectin. Immunohistochemical observations clarified that the proteins were localized in yolk granules and serosa in the diapause egg. These results suggest that OMBP is composed of 30K proteins which were modified with polysaccharides. In addition, the expression of 30K proteins mRNA was observed at early embryonic stage in diapause eggs by RT-PCR analysis. The 30K proteins as OMBP may play an important role in the transport and accumulation of tryptophan metabolites and ommochrome during the formation of serosa. 相似文献
298.
Gangliosides GM1 and GM3 in the living cell membrane form clusters susceptible to cholesterol depletion and chilling 下载免费PDF全文
Fujita A Cheng J Hirakawa M Furukawa K Kusunoki S Fujimoto T 《Molecular biology of the cell》2007,18(6):2112-2122
Presence of microdomains has been postulated in the cell membrane, but two-dimensional distribution of lipid molecules has been difficult to determine in the submicrometer scale. In the present paper, we examined the distribution of gangliosides GM1 and GM3, putative raft molecules in the cell membrane, by immunoelectron microscopy using quick-frozen and freeze-fractured specimens. This method physically immobilized molecules in situ and thus minimized the possibility of artifactual perturbation. By point pattern analysis of immunogold labeling, GM1 was shown to make clusters of <100 nm in diameter in normal mouse fibroblasts. GM1-null fibroblasts were not labeled, but developed a similar clustered pattern when GM1 was administered. On cholesterol depletion or chilling, the clustering of both endogenous and exogenously-loaded GM1 decreased significantly, but the distribution showed marked regional heterogeneity in the cells. GM3 also showed cholesterol-dependent clustering, and although clusters of GM1 and GM3 were found to occasionally coincide, these aggregates were separated in most cases, suggesting the presence of heterogeneous microdomains. The present method enabled to capture the molecular distribution of lipids in the cell membrane, and demonstrated that GM1 and GM3 form clusters that are susceptible to cholesterol depletion and chilling. 相似文献
299.
Egg white ribonuclease was first found in green turtle eggs. The general properties were studied on substrate specificity,
the optimum pH and temperature, and the effect of pH and temperature on the RNase activity. The enzyme studied was specific
for poly (C) and degraded poly (U) at the lower rate and had the pH optimum at 7.0 and the optimum temperature at 40 °C. It
was stable at alkaline range (pH 8.0–10.0) and up to 60 °C in pH 9.0 for 1 h, and unstable at acidic side for all temperatures.
All of the properties studied showed similarity to RNase A. However, the optimum pH, broad range of optimum temperature and
pH stability were different from RNase A. To evaluate the relationship of the structure and enzymatic properties, the 3D-structure
of this enzyme was engineered by program MODELLER using two RNases (2BWL and 2BLZ) as starting models. The differences found
in activity might be affected from the structure of micro environmental changing caused by amino acids deletion and substitution
on the molecule. 相似文献
300.
Toshiaki Ohkuma Masanori Iwase Hiroki Fujii Shinako Kaizu Hitoshi Ide Tamaki Jodai Yohei Kikuchi Yasuhiro Idewaki Yoichiro Hirakawa Udai Nakamura Takanari Kitazono 《PloS one》2015,10(3)