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41.
42.
Arnold JN Wallis R Willis AC Harvey DJ Royle L Dwek RA Rudd PM Sim RB 《The Journal of biological chemistry》2006,281(11):6955-6963
The serum collectin mannan-binding lectin (MBL) binds to oligomannose and GlcNAc-terminating glycans present on microorganisms. Using a commercial affinity chromatography resin containing immobilized MBL we screened human and mouse serum for endogenous MBL-binding targets. We isolated the serum protease inhibitor alpha(2) macroglobulin (alpha2M), a heavily glycosylated thiol ester protein (TEP) composed of four identical 180-kDa subunits, each of which has eight N-linked glycosylation sites. alpha2M has previously been reported to interact with MBL; however, the interaction was not characterized. We investigated the mechanism of formation of complexes between alpha2M and MBL and concluded that they form by the direct binding of oligomannose glycans Man(5-7) occupying Asn-846 on alpha2M to the lectin domains (carbohydrate recognition domains) of MBL. The oligomannose glycans are accessible for lectin binding on both active alpha2M (thiol ester intact) and protease-cleaved alpha2M (thiol ester cleaved). We demonstrate that MBL is able to interact with alpha2M in the fluid phase, but the interaction does not inhibit the binding of MBL to mannan-coated surfaces. In addition to alpha2M, two other members of the TEP family, C3 and C4, which also contain oligomannose glycans, were captured from human serum using the MBL resin. MBL binding may be a conserved feature of the TEPs, dating from their ancestral origins. We suggest that the inhibition of proteases on the surface of microorganisms by an ancestral alpha2M-like TEP may generate "arrays" of oligomannose glycans to which MBL or other lectins can bind. Binding would lead to opsonization or activation of enzyme systems such as complement. 相似文献
43.
Doran PM 《Trends in biotechnology》2006,24(9):426-432
Low production cost is a key factor driving the development of plants and plant tissue cultures for the synthesis of therapeutic and other foreign proteins. Because product yield and concentration exert a major influence on process economics, improving foreign protein accumulation is crucial for enhancing the commercial success of plant-based production systems. Strategies aimed at increasing transgene expression have been effective; however, a critical but poorly understood factor contributing to low foreign protein yield is post-synthesis and/or post-secretion instability and degradation. Loss of foreign protein as result of biological and physical processes such as proteolytic destruction and irreversible surface adsorption can occur in plants and plant culture systems. This review highlights the need to consider such mechanisms and outlines a range of remedial strategies aimed at minimizing foreign protein degradation and loss. 相似文献
44.
Eight new acylated triterpenoid saponins were isolated from the stem bark of Harpullia austro-caledonica along with the known harpuloside (9). Their structures were established using 1D and 2D NMR and mass spectrometry as 3-O-beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylbarringtogenol C (1), 3-O-alpha-L-rhamnopyranosyl-(1-->3)-[beta-D-galactopyranosyl-(1-->2)]-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloyl barringtogenol C (2), 3-O-alpha-L-arabinofuranosyl-(1-->3)-[beta-D-galactopyranosyl-(1-->2)]-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylbarringtogenol C (3), 3-O-alpha-L-arabinofuranosyl-(1-->2)-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylprotoaescigenin (4), 3-O-alpha-L-arabinofuranosyl-(1-->3)-[alpha-L-arabinofuranosyl-(1-->2)]-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloyl protoaescigenin (5), 3-O-alpha-L-arabinofuranosyl-(1-->3)-[beta-D-xylopyranosyl-(1-->2)]-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylprotoaescigenin (6), 3-O-alpha-L-arabinofuranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylprotoaescigenin (7), 3-O-beta-D-xylopyranosyl-(1-->2)-beta-D-glucuronopyranosyl-21 beta, 22 alpha-di-O-angeloylprotoaescigenin (8). The EtOH extract of the stem bark showed in vitro cytotoxic activity against KB cells (90% at 10 microg/ml). At a concentration of 5 microg/ml, the saponin mixture showed haemolytic activity and caused 100% haemolysis of a 10% suspension of sheep erythrocytes. 相似文献
45.
46.
Elias T. Ayuk Bahiru Duguma Steve Franzel Joseph Kengue Matthias Mollet Theophile Tiki-Manga Pauline Zekeng 《Economic botany》1999,53(3):292-301
Dacryodes edulis is one of the most preferred tree species by farmers in the humid lowlands of Cameroon. The fruit of the species figures prominently in cross-boundary trade between Cameroon, Nigeria and Gabon. Although there exist empirical data on the volume of trade of the fruit at this level, no data are available at the farm level. A field survey was undertaken to identify uses, management, and farmers’ improvement objectives and to quantify, at the farm-level, the economic potential of the species. The results of the survey indicate thatD. edulis is widely planted and found mainly in tree crop fields and in home gardens. The fruit is highly consumed and traded. The farm-level value of fruit production reaches $US161 a year per grower or collector. The dead branches of the species are used as firewood and its bark is used as medicine. Desired improvement objectives include increased fruit size, good tasting fruit, high yield and reduced time to bearing. 相似文献
47.
Schaap P 《Development, growth & differentiation》2011,53(4):452-462
The Dictyostelid social amoebas represent one of nature's several inventions of multicellularity. Though normally feeding as single cells, nutrient stress triggers the collection of amoebas into colonies that form delicately shaped fruiting structures in which the cells differentiate into spores and up to three cell types to support the spore mass. Cyclic adenosine monophosphate (cAMP) plays a very dominant role in controlling morphogenesis and cell differentiation in the model species Dictyostelium discoideum. As a secreted chemoattractant cAMP coordinates cell movement during aggregation and fruiting body morphogenesis. Secreted cAMP also controls gene expression at different developmental stages, while intracellular cAMP is extensively used to transduce the effect of other stimuli that control the developmental program. In this review, I present an overview of the different roles of cAMP in the model D. discoideum and I summarize studies aimed to resolve how these roles emerged during Dictyostelid evolution. 相似文献
48.
Hayes CA Karlsson NG Struwe WB Lisacek F Rudd PM Packer NH Campbell MP 《Bioinformatics (Oxford, England)》2011,27(9):1343-1344
Glycosylation is one of the most important post-translational modifications of proteins, known to be involved in pathogen recognition, innate immune response and protection of epithelial membranes. However, when compared to the tools and databases available for the processing of high-throughput proteomic data, the glycomic domain is severely lacking. While tools to assist the analysis of mass spectrometry (MS) and HPLC are continuously improving, there are few resources available to support liquid chromatography (LC)-MS/MS techniques for glycan structure profiling. Here, we present a platform for presenting oligosaccharide structures and fragment data characterized by LC-MS/MS strategies. The database is annotated with high-quality datasets and is designed to extend and reinforce those standards and ontologies developed by existing glycomics databases. AVAILABILITY: http://www.unicarb-db.org 相似文献
49.
Odiere MR Opisa S Odhiambo G Jura WG Ayisi JM Karanja DM Mwinzi PN 《Parasitology》2011,138(12):1569-1577
This cross-sectional study determined the prevalence and distribution of schistosome and soil-transmitted helminth (STH) infections among 1,308 children aged 10-18 years in 34 primary schools in 8 informal urban settlements in Kisumu City, western Kenya. Stool samples were collected and examined for eggs of Schistosoma mansoni and STH (Hookworms, Ascaris lumbricoides and Trichuris trichiura) using the Kato-Katz technique. Haematuria was used as a proxy indicator of urinary schistosomiasis. Schools and water bodies were mapped using a geographical information system. Overall, 34% of children were infected with one or more helminth species whereas 16·2% of children were infected with one or more STH species. Schools in closest proximity to Lake Victoria and River Nyamasaria had the highest S. mansoni prevalence while schools with STH were more homogenously distributed. Mean school prevalence of S. mansoni infection was 21% (range=0-69·7%), S. haematobium 3·6% (range=0-12%), hookworms 6·1% (range=0-20%), A. lumbricoides 4·9% (range=0-18·4%), and T. trichiura 7·7% (range=0-18·6%). Helminth-related morbidities were not associated with infection. Our study demonstrates that schistosomiasis and STH are important health priorities among schools in informal settlements of Kisumu City, and highlights the need for routine deworming in similar settings. 相似文献
50.
Simon C. Andrews Madeleine C. Brady Amyra Treffry John M. Williams Stephen Manna Maud I. Cleton Wim de Bruijn Pauline M. Harrison 《Biometals》1988,1(1):33-42
Summary Haemosiderin has been isolated from siderosomes and ferritin from the cytosol of livers of rats iron-loaded by intraperitoneal injections of iron-dextran. Siderosomal haermosiderin, like ferritin, was shown by electron diffraction to contain iron mainly in the form of small particles of ferrihydrite (5Fe2O3 · 9H2O), with average particle diameter of 5.36±1.31 nm (SD), less than that of ferritin iron-cores (6.14±1.18 nm). Mössbauer spectra of both iron-storage complexes are also similar, except that the blocking temperature,T
B, for haemosiderin (23 K) is lower than that of ferritin (35 K). These values are consistent with their differences in particle volumes assuming identical magnetic anisotropy constants. Measurements of P/Fe ratios by electron probe microanalysis showed the presence of phosphorus in rat liver haemosiderin, but much of it was lost on extensive dialysis. The presence of peptides reacting with anti-ferritin antisera and the similarities in the structures of their iron components are consistent with the view that rat liver haemosiderin arises by degradation of ferritin polypeptides, but its peptide pattern is different from that found in human-thalassaemia haemosiderin. The blocking temperature, 35 K, for rat liver ferritin is near to that reported, 40 K, for human-thalassaemia spleen ferritin. However, the haemosiderin isolated from this tissue, in contrast to that from rat liver, had aT
B higher than that of ferritin. The iron availability of haemosiderins from rat liver and human-thalassaemic spleen to a hydroxypyridinone chelator also differed. That from rat liver was equal to or greater, and that from human spleen was markedly less, than the iron availability from either of the associated ferritins, which were equivalent. The differences in properties of the two types of haemosiderin may reflect their origins from primary or secondary iron overload and differences in the duration of the overload. 相似文献