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991.
Ikeda I Konno R Shimizu T Ide T Takahashi N Kawada T Nagao K Inoue N Yanagita T Hamada T Morinaga Y Tomoyori H Imaizumi K Suzuki K 《Biochimica et biophysica acta》2006,1760(5):800-807
Dietary campest-5-en-3-one (campestenone), an oxidized derivative of campesterol, significantly reduced visceral fat weight and the concentration of triacylglycerol in serum and liver of rats. Dietary campestenone dramatically increased the activities and the mRNA expressions of mitochondrial and peroxisomal enzymes involved in beta-oxidation in the liver. Campestenone activated human peroxisome proliferator-activated receptor (PPAR) alpha as determined using the novel GAL4 ligand-binding domain chimera assay system with coactivator coexpression. In contrast, dietary campestenone reduced the activities and the mRNA expressions of enzymes involved in fatty acid synthesis, except for the malic enzyme. Dietary campestenone decreased the sterol regulatory element binding protein-1 (SREBP-1) mRNA level. Energy expenditure was significantly higher in the feeding of campestenone in rats. Dietary campestenone reduced hepatic cholesterol concentration and increased fecal excretion of neutral steroids originated from cholesterol. Lymphatic absorption of cholesterol was reduced by the coadministration of campestenone in rats cannulated in the thoracic duct. These observations suggest a possibility that campestenone has an ability to prevent coronary heart disease by improving obesity and abnormality of lipid metabolism. 相似文献
992.
Yuriko Abe Hiroko Akao Hiroshi Takashima Hidetomo Mukai 《Inorganica chimica acta》2006,359(10):3147-3155
A series of nickel(II) salen complexes containing 4-substituted alkoxy chains of aromatic rings, [Ni((4-CnH2n + 1O)2salen)] (n = 3 (1), 4 (2), 6 (3), 8 (4), 10 (5), 12 (6), 14 (7), 16 (8), 18 (9), and 20 (10)), and their parent complex, [Ni((4-HO)2salen)] (11) (salen = N,N′-ethylenebis(salicylideneiminato)), have been prepared and mesomorphic properties have been investigated. An X-ray crystallographic analysis revealed that complex 11 · 2DMF has one-dimensional stacking structure supported by the π-π interaction between the six-membered chelate and aromatic rings with the NiNi distances of alternatively 3.3957 and 3.7224 Å and that complex 3 is formed by one-dimensional stacking by weak CH?O type hydrogen bonded interaction between the five-membered chelate ring and phenoxo atoms of the dramatically distorted salen moieties with the NiNi distance of 5.994 Å. Complexes 1-6 did not exhibit any mesophases. On the other hand, complexes 7-10 with longer alkoxy chains of n = 14-20 showed an unusual metallomesogen of a lamello-columnar mesophase within the smectic layers with an interlamellar distance of 31.1 Å (7), 33.6 Å (8), 37.1 Å (9), and 39.5 Å (10) and nearly constant stacking distance of 6.19-6.24 Å between the inter-dimers, irrespective of the variation of the alkoxy chain lengths by the X-ray diffraction measurements of the liquid crystal. The relationship between molecular assemblies and mesomorphic properties is discussed. 相似文献
993.
Nishida N Motojima F Idota M Fujikawa H Yoshida M Shimada I Kato K 《Journal of biochemistry》2006,140(4):591-598
Bacterial chaperonin GroEL with a molecular mass of 800 kDa was studied by (13)C NMR spectroscopy. Carbonyl carbons of GroEL were labeled with (13)C in an amino acid specific manner in order to reduce the number of signals to be observed in the spectrum. Combination of selective labeling and site-directed mutagenesis enabled us to establish the sequence specific assignment of the (13)C resonances from GroEL. ADP-binding induced a chemical shift change of Tyr478 in the equatorial domain and His401 in the intermediate domain, but little of Tyr203 in the apical domain. Upon complex formation with co-chaperonin GroES in the presence of ADP, Tyr478 exhibits two peaks that would originate from the cis and trans rings of the asymmetric GroEL-GroES complex. Comparison between the line width of the GroEL resonances and those from GroES in complex with GroEL revealed broadening disproportionate to the size of GroEL, implying the existence of conformational fluctuations which may be pertinent to the chaperone activity. Based on these results, we concluded that (13)C NMR observation in combination with selective labeling and site-directed mutagenesis can be utilized for probing the conformational change and dynamics of the extremely large molecules that are inaccessible with current NMR methods. 相似文献
994.
In the current studies, we used Lineweaver-Burke analysis to examine the role of 1-hydroxybenzotriazole (HBT) in the oxidation of various compounds by laccase from Trametes versicolor. At low concentrations, HBT was a competitive inhibitor of the oxidation, but at high concentrations, it was a noncompetitive inhibitor. Analysis of the oxidation of ferrocytochrome c by the laccase-HBT couple showed that increasing the concentration of ferrocytochrome c did not affect the V(max) but reduced the apparent K(m). In addition, in the manganese peroxidase-Mn(II) reaction, which is a typical oxidation system by mediator, the apparent K(m) and V(max) increased as the concentration of the substrate 2,6-dimethoxyphenol was increased. These results indicate that HBT is involved in the binding of laccase and substrates that laccase cannot oxidize alone. 相似文献
995.
996.
Ozcelik P Bezirci FB Suzuki Y Uzawa H Nishida Y Kobayashi K Suzuki T Miyamoto D Nagatake T Ahmed K 《Microbiology and immunology》2006,50(12):967-970
Moraxella catarrhalis is one of the major pathogens of respiratory and middle ear infections. Attachment of this bacterium to the surface of human pharyngeal epithelial cells is the first step in the pathogenesis of infections. This study revealed that sulfatide might act as a binding molecule for the attachment of M. catarrhalis to human pharyngeal epithelial cells. Furthermore, six different synthetic sulfatides were found to inhibit the attachment of M. catarrhalis significantly at an optimum concentration of 10 microg/ml. Synthetic sulfatides may have the potential to be used as a therapy to prevent M. catarrhalis infections. 相似文献
997.
Nagayoshi C Tokunaga H Hayashi A Harazono H Hamasaki K Ando A Tokunaga M 《Protein and peptide letters》2006,13(6):611-615
Enzymes from extremely halophilic archaea require high concentration of salts for their proper folding and consequently are expressed as an unfolded and inactive form in Escherichia coli. Moderate halophile, which accumulates protein stabilizers, i.e., compatible solutes, is an attractive host cell for the recombinant production of heterologous proteins, since such protein stabilizers may help folding of expressed proteins. Here, we succeeded in efficient expression and purification to homogeneity of recombinant haloarchaeal nucleoside diphosphate kinase (HsNDK) in moderate halophile using newly isolated strong porin promoter. 相似文献
998.
Bordetella pertussis, the causative agent of whooping cough, produces a complex hetero-oligomeric exotoxin, named pertussis toxin (PTX), which is responsible for several of the clinical manifestations associated with whooping cough. The toxin is composed of five dissimilar subunits, named S1 through S5 and arranged in a hexameric structure with a 1S1:1S2:1S3:2S4:1S5 stoichiometry. Although S2 and S3 share 70% amino acid identity, these two subunits were previously thought not to be able to substitute for each other in toxin assembly/secretion and the biological activities of PTX. Here, we show that toxin analogues containing two S3 subunits and lacking S2 (PTXdeltaS2), or containing two S2 subunits and lacking S3 (PTXdeltaS3), can be produced, assembled and secreted by B. pertussis strains, in which the S2-encoding cistron or the S3-coding cistrons have been inactivated by internal in-frame deletions that avoid downstream effects. In fact, PTXdeltaS3 was produced in higher amounts in the bacterial culture supernatants than natural PTX, whereas PTXdeltaS2 was produced in lower amounts than PTX. The action of the toxin analogues on the clustering of Chinese Hamster Ovary cells was also affected differentially by the S2-S3 substitution. These toxin analogues constitute thus interesting probes for the study of cellular functions, in particular immune cell functions, for which natural PTX has already shown its usefulness. 相似文献
999.
Hung J Yang TL Urrutia TF Li R Perry CA Hata H Cogger EA Moriarty DJ Caudill MA 《The Journal of nutritional biochemistry》2006,17(11):728-734
The effectiveness of additional food folate in improving folate status in humans is uncertain particularly in people with the common genetic variant (677 C-->T) in the methylenetetrahydrofolate reductase (MTHFR) gene. To examine the effect of a doubling of food folate consumption on folate status response variables, women (n=32; 18-46 years) with the MTHFR 677 CC or TT genotype consumed either 400 (n=15; 7 CC and 8 TT) or 800 (n=17; 8 CC and 9 TT) microg/day of dietary folate equivalents (DFE) derived exclusively from naturally occurring food folate for 12 weeks. A repeated measures two-factor ANOVA was used to examine the effect of the dietary treatment, the MTHFR C677T genotype and their interactions on serum folate, RBC folate and plasma total homocysteine (tHcy) during the last 3 weeks of the study. Consumption of 800 microg DFE/day resulted in serum folate concentrations that were 67% (P=.005) higher than consumption of 400 microg DFE/day (18.6+/-2.9 vs. 31.0+/-2.7 nmol/L, respectively) and RBC folate concentrations that were 33% (P=.001) higher (1172+/-75 vs. 1559+/-70 nmol/L, respectively). Serum folate (P=.065) and RBC folate (P=.022) concentrations were lower and plasma tHcy was higher (P=.039) in women with the MTHFR 677 TT genotype relative to the CC genotype. However, no genotype by dietary treatment interaction was detected. These data suggest that a doubling of food folate intake will lead to marked improvements in folate status in women with the MTHFR 677 CC or TT genotype. 相似文献
1000.
Matsushita-Oikawa H Komatsu M Iida-Tanaka N Sakagami H Kanamori T Matsumoto I Seno N Ogawa H 《Glycobiology》2006,16(10):891-901
Beta-glucuronidase is a lysosomal enzyme that plays an essential role in normal turnover of glycosaminoglycans and remodeling of the extracellular matrix components in both physiological and inflammatory states. The regulation mechanisms of enzyme activity and protein targeting of beta-glucuronidase have implications for the development of a variety of therapeutics. In this study, the effectiveness of various carbohydrate-immobilized adsorbents for the isolation of bovine liver beta-glucuronidase (BLG) from other glycosidases was tested. Beta-glucuronidase and contaminating glycosidases in commercial BLG preparations bound to and were coeluted from adsorbents immobilized with the substrate or an inhibitor of beta-glucuronidase, whereas beta-glucuronidase was found to bind exclusively with lactamyl-Sepharose among the adsorbents tested and to be effectively separated from other enzymes. Binding and elution studies demonstrated that the interaction of beta-glucuronidase with lactamyl-Sepharose is pH dependent and carbohydrate specific. BLG was purified to homogeneity by lactamyl affinity chromatography and subsequent anion-exchange high-performance liquid chromatography (HPLC). Lactose was found to activate beta-glucuronidase noncompetitively, indicating that the lactose-binding site is different from the substrate-binding site. Binding studies with biotinyl glycoproteins, lipids, and synthetic sugar probes revealed that beta-glucuronidase binds to N-acetyllactosamine/lactose-containing glycoconjugates at neutral pH. The results indicated the presence of N-acetyllactosamine/lactose-binding activity in BLG and provided an effective purification method utilizing the novel carbohydrate binding activity. The biological significance of the carbohydrate-specific interaction of beta-glucuronidase, which is different from the substrate recognition, is discussed. 相似文献