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491.
The embryonic development of skeletal muscle proceeds by the adherence and fusion of myoblast cells to form multinucleated myotubes. In the present study, enzymes in the dolichol pathway for asparagine-linked glycoprotein synthesis and oligosaccharide chain composition were characterized in myoblasts and myotubes derived from the C2 (mouse) muscle cell line. The N-acetylglucosaminyltransferase responsible for chain initiation and the mannosyl- and glucosyltransferases for Dol-P-Man and Dol-P-Glc synthesis were characterized with respect to substrate, cation, and detergent dependence. Time course studies in the absence and presence of exogenous Dol-P revealed that myoblasts had a two- to threefold higher capacity than myotubes for Dol-sugar synthesis. Pulse-chase experiments following the elongation of the Dol-oligosaccharide by intact cells showed myoblasts to label oligosaccharide intermediates approximately fourfold greater than myotubes; myotubes, however, were more efficient than myoblasts for converting the intermediates to the glucosylated Dol-tetradecasaccharide. Oligosaccharide chains isolated from sarcolemma glycopeptides were analyzed by Con A, WGA, and QAE chromatography. There were no differences between myoblast and myotube oligosaccharides with respect to the proportion of tri-tetraantennary complex, biantennary complex, and high mannose chains. Hybrid chains were not detected. The major high mannose chain contained nine mannose residues. Sialyltransferase activity was identical. The results suggest that higher levels of Dol-P and protein acceptor contribute to the greater degree of protein glycosylation in myoblast vs myotube muscle cells. 相似文献
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Blondeel Haben Remy Elyn Perring Michael P. Landuyt Dries Bodé Samuel De Frenne Pieter Boeckx Pascal Verheyen Kris 《Plant and Soil》2019,442(1-2):199-213
Plant and Soil - Shrub encroachment has profound influences on regional carbon cycling. However, few studies have examined the changes in soil organic carbon (SOC) components at the molecular level... 相似文献
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Size reduction of galactosylated PEI/DNA complexes improves lectin-mediated gene transfer into hepatocytes. 总被引:4,自引:0,他引:4
Hepatocytes are interesting targets for gene therapy applications. Several hepatocyte-directed gene delivery vectors have been described. For example, simple galactosyl residues coupled to polyethylenimine (PEI) gave an efficient vector which selectively transfected hepatocytes via the asialoglycoprotein receptor-mediated endocytosis [Zanta, M. A., et al. (1997) Bioconjugate Chem. 8, 839-844]. However, the large size of these galactosylated PEI/DNA complexes prevented their use in vivo. We have investigated the role of the saccharide length on the size of glycosylated-PEI/DNA particles. When 5% of the PEI nitrogens were grafted with a linear tetragalactose structure (lGal4), small and stable particles were formed upon complexation with plasmid DNA. These particles were essentially toroids having a size of 50-80 nm and a zeta-potential close to neutrality. Moreover, these slightly charged PEI-lGal4/DNA complexes were as selective as the previously described galactosylated-PEI vector to transfect hepatocytes, but in addition, they were more efficient. It is expected that the properties of the PEI-lGal4/DNA complexes may increase their diffusion into the liver and their efficiency to transfect hepatocytes. 相似文献
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Hexyl-alpha-chymotrypsin, a hydrophobic derivative of the enzyme, is explored for the proteinase-catalyzed ester synthesis reaction with N-acetyl-L-tyrosine and ethanol. To guarantee the preservation of the enzyme activity and to allow for the extraction of the product in the organic phase, a biphasic system was used. The Vm increased for the modified enzyme. This phenomenon was linked to the modification of the protein as demonstrated by its chemical denaturation with sodium dodecyl sulfate. 相似文献
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