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1.
Kiyomi Kikugawa Kazuyuki Hiramoto Yutaka Okamoto Yo-Ko Hasegawa 《Free radical research》1994,21(6):399-408
Nitrogen dioxide less than 100 ppm in air induced lipid peroxidation of liposome composed of l-palmitoyl-2-arachidonylphosphatidylcholine as assessed by thiobarbituric acid reactivity. The nitrogen dioxide-induced lipid peroxidation was enhanced by cysteine, glutathione and bovine serum albumin. While the activity of nitrogen dioxide in air to induce single strand breaks of supercoiled plasmid DNA was low, the breaking was remarkably enhanced by cysteine, glutathione and bovine serum albumin. ESR spin trapping using 5,5-dimethyl-1-pyrroline N-oxide showed that certain strong oxidant(s) were generated by interaction of nitrogen dioxide and cysteine. The spin trapping using 3,5-dibromo-4-nitrosobenzene-sulfonate suggested that sulfur-containing radicals were generated by interaction of nitrogen dioxide and cysteine or glutathione. Hence, certain sulfur-containing radicals generated by the interaction which could effectively induce lipid peroxidation and DNA strand breaks. 相似文献
2.
3.
Shigeki Takeura Hiizu Aoki Tatsuya Tsurumi Yukihiro Nishiyama Hisashi Fujioka Saiji Yoshii Koichiro Maeno 《Microbiology and immunology》1984,28(4):427-437
Host-dependent restriction of influenza B virus replication in L cells was analysed in comparison with productive infection in MDCK or 1–5C-4 cells. The synthesis and intracellular distribution of virus-specific proteins and the production of cytoplasmic ribonucleoproteins in nonpermissive L cells were similar to those in permissive MDCK cells. However, an electron microscopic study of infected L cells showed neither extracellular virions nor budding virus particles on the cell surface, in contrast to MDCK cells which produced numerous virus particles. PAGE analysis of the plasma membrane isolated from the cells demonstrated no significant difference in the composition of viral polypeptides between permissive 1-5C-4 and nonpermissive L cells. It was noted that the abortiveness of influenza B virus infection in L cells may be due to a defect in host cell function involved in the initiation of virus budding. 相似文献
4.
Changes in Targeting Efficiencies of Proteins to Plant Microbodies Caused by Amino Acid Substitutions in the Carboxy-terminal Tripeptide 总被引:7,自引:0,他引:7
Hayashi Makoto; Aoki Masahiro; Kondo Maki; Nishimura Mikio 《Plant & cell physiology》1997,38(6):759-768
It has been demonstrated that the carboxyl terminus of microbodyenzymes functions as a targeting signal to microbodies in higherplants. We have examined an ability of 24 carboxy-terminal aminoacid sequences to facilitate the transport of a cytosolic passengerprotein, ß-glucuroni-dase, into microbodies in greencotyledonary cells of trans-genic Arabidopsis. Immunoelectronmicroscopic analysis revealed that carboxy-terminal tripeptidesequences of the form [C/A/S/P]-[K/R]-[I/L/M] function as amicrobody-targeting signal, although tripeptides with prolineat the first amino acid position and isoleucine at the carboxylterminus show weak targeting efficiencies. All known micro-bodyenzymes that are synthesized in a form similar in size to themature molecule, except catalase, contain one of these tripeptidesequences at their carboxyl terminus. (Received April 14, 1997; Accepted April 8, 1997) 相似文献
5.
Y S Ho P J Sheffield J Masuyama H Arai J Li J Aoki K Inoue U Derewenda Z S Derewenda 《Protein engineering》1999,12(8):693-700
Platelet-activating factor acetylhydrolases (PAF-AHs) are unique PLA2s which hydrolyze the sn-2 ester linkage in PAF-like phospholipids with a marked preference for very short acyl chains, typically acetyl. The recent solution of the crystal structure of the alpha(1) catalytic subunit of isoform Ib of bovine brain intracellular PAF-AH at 1.7 A resolution paved the way for a detailed examination of the molecular basis of substrate specificity in this enzyme. The crystal structure suggests that the side chains of Thr103, Leu48 and Leu194 are involved in substrate recognition. Three single site mutants (L48A, T103S and L194A) were overexpressed and their structures were solved to 2.3 A resolution or better by X-ray diffraction methods. Enzyme kinetics showed that, compared with wild-type protein, all three mutants have higher relative activity against phospholipids with sn-2 acyl chains longer than an acetyl. However, for each of the mutants we observed an unexpected and substantial reduction in the V(max) of the reaction. These results are consistent with the model in which residues Leu48, Thr103 and Leu194 indeed contribute to substrate specificity and in addition suggest that the integrity of the specificity pocket is critical for the expression of full catalytic function, thus conferring very high substrate selectivity on the enzyme. 相似文献
6.
Stimulation of death receptors (Fas on human T-cell leukemia Jurkat cells and tumor necrosis factor receptor-1 on human monoblastic leukemia U937 cells) triggers the specific degradation of 28S ribosomal RNA, and this process may contribute to cell death through the inhibition of protein synthesis. We have developed an analytical method using a polyacrylamide-agarose composite gel to evaluate ribosomal subunits in apoptotic cells (human breast carcinoma MCF-7 cells treated with staurosporine and human 293T cells irradiated with ultraviolet light were used in addition to the two apoptosis systems described above). No alterations were detected by this method, suggesting that apoptosis, including the process of ribosomal RNA degradation, does not cause fragmentation or extensive conformational changes in the ribosome. We also examined the status of 21 different ribosomal proteins in apoptotic cells by immunoblotting with polyclonal antibodies. S11 was specifically downregulated in apoptotic MCF-7 cells and in other apoptotic breast carcinoma cells. Previous studies have shown that S11 is heterogeneously expressed in cancer cells. Taken together, it appears that particular intracellular environments regulate the expression of S11 protein. However, the mechanism by which this process is modulated is as yet unknown. Furthermore, we have demonstrated that our composite gel electrophoresis system can efficiently detect ubiquitination of ribosomal subunits. 相似文献
7.
Atsunori Kashiwagi Kazuyuki Sasaki Tamio Noguchi Takehiko Tanaka 《Biochimica et Biophysica Acta (BBA)/General Subjects》1979,582(2):221-233
A factor responsible for stimulating an increase in ornithine decarboxylase activity in the liver of mice was found in tumor cell-free ascites fluid of mice 3 days after inoculation of tumor cells. The factor was purified about 70-fold in 25% yield from tumor cell-free ascites fluid. As little as 1 μg of protein of purified fraction, injected intraperitoneally into normal mice, significantly increased the activity of ornithine decarboxylase in the liver. The most active preparation of the factor formed two major protein bands on analytical polyacrylamide gel electrophoresis and both these bands stained with periodic acid-Schiff's reagent. The factor was a heat-labile, alkaline-stable, acidic protein with a molecular weight of more than 300 000. It was inactivated by treatment with 10 mM dithiothreitol, 5M urea, pronase or mixed glycosidase, but was stable on treatment with DNAase, RNAase or neuraminidase. 相似文献
8.
M Noguchi H Adachi S Sato T Honda S Ohnishi E Aoki K Torizuka 《Endocrinologia japonica》1987,34(5):727-736
We investigated cholecystokinin (CCK) receptors on isolated gastric chief cells from guinea pig. CCK stimulated pepsinogen secretion from chief cells at the same efficacy as that induced by carbamylcholine. Binding of 125I-labeled CCK-33 (125I-CCK) to chief cells was temperature-dependent, and was saturable and reversible at 37 degrees C. Hofstee plots of the ability of CCK-8 to inhibit binding of 125I-CCK showed a linear regression line, suggesting that CCK receptors possessed one binding site. The dissociation constant of the binding site was calculated to be 3.8 x 10(-10) M. The dose-response curve of CCK for pepsinogen secretion was superimposed on that for the binding to its receptors. These results indicated that gastric chief cells from the guinea pig possess CCK receptors that relate closely to the action of CCK involved in pepsinogen secretion. 相似文献
9.
Kazuyuki Tao Kozu Makino Shuji Yonei Atsuo Nakata Hideo Shinagawa 《Molecular & general genetics : MGG》1989,218(3):371-376
Summary Treatment of Escherichia coli and Salmonella typhimurium cells with a low dose of hydrogen peroxide induces expression of a large number of genes, and confers resistance to oxidative stresses. The oxyR gene encodes a positive regulatory protein for a subset of these genes involved in the defense against oxidative damage. We cloned a DNA fragment that contains the E. coli oxyR region on a plasmid vector, and analyzed the nucleotide sequence of the gene. The amino acid sequence of OxyR protein, deduced from the nucleotide sequence, shows a high degree of homology to the sequences of a number of bacterial activator proteins including LysR, cysB, IlvY, MetR and NodD. The product of the oxyR gene identified by the maxicell procedure was a 34 kDa protein, which agrees with the size predicted from the nucleotide sequence of the gene. 相似文献
10.
The role of thromboxane A2 [TxA2] in liver injury in mice 总被引:1,自引:0,他引:1
The role of thromboxane A2 (TxA2) in CCl4-induced liver disease was investigated in mice. Significant elevation of TxB2 in the liver was observed 6 hours after the injection of CCl4. Administration of OKY-046, a selective TxA2 synthetase inhibitor (10 and 50 mg/kg) and ONO-3708, a TxA2 receptor antagonist, (0.5, 1 and 2 mg/Kg) suppressed the elevation of serum GOT and GPT levels and histopathological changes of the liver. In addition, OKY-046 inhibited the elevation of TxB2 in the liver. When U-46619, a stable TxA2 mimetic was injected i.v. into the mice, clear elevation of serum GOT and GPT levels and histopathological score of the liver were observed. These results suggest that TxA2 play a role for the onset of CCl4-induced liver injury in mice. 相似文献