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1.
Abhishek Chatterjee Celia Caballero-Franco Dannika Bakker Stephanie Totten Armando Jardim 《The Journal of biological chemistry》2015,290(42):25579-25594
Enterohemorrhagic Escherichia coli is a causative agent of gastrointestinal and diarrheal diseases. Pathogenesis associated with enterohemorrhagic E. coli involves direct delivery of virulence factors from the bacteria into epithelial cell cytosol via a syringe-like organelle known as the type III secretion system. The type III secretion system protein EspD is a critical factor required for formation of a translocation pore on the host cell membrane. Here, we show that recombinant EspD spontaneously integrates into large unilamellar vesicle (LUV) lipid bilayers; however, pore formation required incorporation of anionic phospholipids such as phosphatidylserine and an acidic pH. Leakage assays performed with fluorescent dextrans confirmed that EspD formed a structure with an inner diameter of ∼2.5 nm. Protease mapping indicated that the two transmembrane helical hairpin of EspD penetrated the lipid layer positioning the N- and C-terminal domains on the extralumenal surface of LUVs. Finally, a combination of glutaraldehyde cross-linking and rate zonal centrifugation suggested that EspD in LUV membranes forms an ∼280–320-kDa oligomeric structure consisting of ∼6–7 subunits. 相似文献
2.
1. Methyl retinoate has been converted into methyl 5,6-monoepoxyretinoate by reaction with monoperphthalic acid. The epoxy acid ester on alkaline hydrolysis gave 5,6-monoepoxyretinoic acid. 2. Treatment of the 5,6-monoepoxy compounds with ethanolic hydrochloric acid gave the corresponding 5,8-epoxy (furanoid) compounds. 3. With lithium aluminium hydride, the acid and the ester groups were selectively reduced to primary alcohols. 4. Administration of methyl 5,6-monoepoxyretinoate intraperitoneally and subcutaneously had good growth response in vitamin A-deficient rats. 5. 5,6-Monoepoxyretinoic acid, when given intraperitoneally as the sodium salt, was 157% as active as all-trans-retinyl acetate. 6. Methyl 5,6-monoepoxyretinoate was hydrolysed to the epoxy acid by rat-liver homogenate. It had 35% of the biological activity of all-trans-retinyl acetate in the rat when given orally. 相似文献
3.
1. Glycoproteins were isolated from the plasma of sheep, goat, cow, buffalo and monkey. They were homogeneous by electrophoresis; on ultracentrifugation, a faster-sedimenting fraction, to an extent of 5–8% only, was observed in each case. 2. Similar physical properties were exhibited by these glycoproteins and they each have a molecular weight of about 105000. 3. In chemical composition, differences have been observed and the glycoproteins can be classified into three groups: (a) sheep and goat glycoproteins; (b) cow and buffalo glycoproteins; (c) monkey glycoprotein. Glucose, galactosamine and N-terminal amino acid were absent from these proteins. 4. These glycoproteins were trypsin inhibitors and prolonged the clotting time of plasma. 相似文献
4.
5.
Luísa M. D. R. S. Martins Armando J. L. Pombeiro Richard A. Henderson 《Inorganica chimica acta》1996,250(1-2):311-315
The kinetics of the displacement reactions of the bromide ligands of trans-[FeBr2(depe)2] (depe = Et2PCH2CH2PEt2) by the organonitrile NCCH2C6H4OMe-4, in tetrahydrofuran (either in the absence or in the presence of added Br−), to give the corresponding mono- and dinitrile complexes trans-[FeBr(NCCH2C6H4OMe-4)(depe)2]+ and trans-[Fe(NCCH2C6H4OMe-4)2(depe)2]2+, have been investigated by stopped-flow spectrophotometry. The substitution reaction occurs by a mechanism involving rate-limiting dissociation of bromo ligands to form the unsaturated intermediates [FeBr(depe)2]+ (k1 = 1.52 ± 0.02 s−1) and [Fe(NCR)(depe)2]2+ (k3 = 0.063 ± 0.008 s−1) which add the nitrile ligand to form those nitrile complexes. The competition between the nitrile and Br− for such metal centres has also been investigated and a stronger inhibiting effect of added Br− is observed for the substitution of the second bromo ligand relative to the first one. The kinetic data are rationalized in terms of π-electronic effects of these unsaturated metal centres and of the bromide and nitrile ligands. 相似文献
6.
Márcia Camargo-De-Morais Marta De Freitas Angela G. De Mattos Nádia Schröder Ana C. Zilles Carla S. F. Lisboa Nice Arteni Armando Barlem Rejane Schierholt Guilherme Zwetsch Carlos A. B. Souza Regina Pessoa-Pureur Carlos A. Netto 《Neurochemical research》1996,21(5):595-602
Neurofilaments subunits (NF-H, NF-M, NF-L) and glial fibrillary acidic protein (GFAP) were investigated in the hippocampus
of rats after distinct periods of reperfusion (1 to 15 days) following 20 min of transient global forebrain ischemia in the
rat. In vitro [14Ca]leucine incorporation was not altered until 48 h after the ischemic insult, however concentration of intermediate filament
subunits significantly decreased in this period. Three days after the insult, leucine incorporation significantly increased
while the concentration NF-H, NF-M, and NF-L were still diminished after 15 days of reperfusion. In vitro incorporation of32P into NF-M and NF-L suffered immediately after ischemia, but returned to control values after two days of reperfusion. GFAP
levels decreased immediately after ischemia but quickly recovered and significantly peaked from 7 to 10 days after the insult.
These results suggest that transient ischemia followed by reperfusion causes proteolysis of intermediate filaments in the
hippocampus, and that proteolysis could be facilitated by diminished phosphorylation levels of NF-M and NF-L. 相似文献
7.
Lenzi Kaden Armando J. L. Pombeiro Yu Wang Ulrich Abram 《Inorganica chimica acta》1995,230(1-2):189-192
The Tc(I) mixed-ligand complex, trans-[Tc(dppe)2(butNC)2](PF6) (dppe=bis(diphenylphosphino)ethane, butNC=tert-butyl-isocyanide) has been prepared from [Tc(tu−S)63+ (tu-S=thiourea) and a mixture of both ligands. The compound crystallizes triclinic in the space group ). The technetium atom has a slightly distorted octahedral coordination sphere with the isocyanide ligands in trans-position to each other. By cyclic voltammetry, at a Pt electrode, trans-[Tc(dppe)2(butNC)2](PF6) undergoes a single electron reversible oxidation at E1/2ox=0.91 V versus SCE. 相似文献
8.
Eduardo A. Moscone Josef Loidl Friedrich Ehrendorfer Armando T. Hunziker 《American journal of botany》1995,82(2):276-287
Nucleolar activity of 22 samples belonging to nine diploid species of Capsicum was analyzed in somatic metaphases and interphase nuclei. They are: C, chacoënse, C. parvifolium, C. frutescens, C. chinense, C. annuum var. annuum, C. baccatum var. pendulum, C. pubescens, all with 2n = 24, and C. mirabile var. mirabile and C. campylopodium with 2n = 26. Silver staining was applied for the first time in Capsicum, providing useful markers for chromosome identification in combination with other banding techniques already employed in the genus. From two to eight AgNORs (silver-stained nucleolus organizing regions) were found in the diploid complement of the taxa studied. Nucleolar organizers are located at secondary constrictions of chromosomes which are conventionally stained or banded (C-banding or fluorochrome banding). Polymorphism of AgNORs and attached satellites often occurs. Nucleoli are usually fused to a variable extent. Number and position of active rDNA loci are variable not only between but also within species and populations. Homologies in position of NORs between species were established. The data obtained are related to previous conclusions on phylogenetic relationships in Capsicum. Possible trends of karyotype evolution concerning nucleolar organizers are discussed, and four NORs in the diploid complement (on chromosome pairs #1 [m] and #12 [st]) are regarded as the plesiomorphic condition. 相似文献
9.
10.
Parodi Armando J. Blank Edward W. Peterson Jerry Ceriani Roberto 《Molecular and cellular biochemistry》1984,58(1-2):157-163
Summary Membranes isolated from mouse and human milk fat globules were found to contain the enzymes responsible for the synthesis of dolichol monophosphate mannose and dolichol monophosphate glucose as well as those involved in the transference of the glycosyl residues from the two dolichol derivatives to dolichol diphosphate oligosaccharides. The levels of most of the enzymes were comparable to those found in mouse mammary gland microsomes. The presence of enzymes involved in protein glycosylation via dolichol derivatives in the milk fat globule membrane provides evidence in favor of an outward flow of membrane components from the rough endoplasmic reticulum, where these enzymes are active in vivo, towards the cell surface. 相似文献