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C2-hydroxyglycosylation with glycal donors. Probing the mechanism of sulfonium-mediated oxygen transfer to glycal enol ethers.The C2-hydroxyglycosylation reaction employing the reagent combination of a diaryl sulfoxide and triflic anhydride offers a novel method for glycal assembly whereby a hydroxyl functionality is stereoselectively installed at the C2-position of a glycal donor with concomitant glycosylation of a nucleophilic acceptor. Mechanistic investigations into this reaction revealed a novel process for sulfonium-mediated oxidation of glycal enol ethers in which the sulfoxide oxygen atom is stereoselectively transferred to the C2-position of the glycal. involves initial formation of a C1[bond]O linkage followed by O-migration to C2, leading to the generation of an intermediate glycosyl 1,2-anhydropyranoside that serves as an in situ glycosylating agent. These findings are consistent with the initial formation of a C2-sulfonium[bond]C1-oxosulfonium pyranosyl species upon activation of the glycal donor with Aryl(2)SO x Tf(2)O.

Autotaxin is an N-linked glycoprotein but the sugar moieties are not needed for Autotaxin is a 125kD autocrine motility factor that stimulates both random and directed motility in producing the human A58 melanoma cell line. The recently cloned autotaxin has been demonstrated to bind strongly and specifically to concanavalin A (con A). In this study, we show that the oligosaccharide side chains on autotaxin are exclusively asparagine linked, since N-glycosidase F, but not neuraminidase or O-glycosidase, decreases the protein molecular mass to 0-5kD, which is the calculated molecular mass of the deduced autotaxin polypeptide. Furthermore, 2'-fucosyllactose of oligosaccharide side chains by N-glycosidase F can be performed under mild conditions that retain motility-stimulating activity, suggesting that the oligosaccharide side chains are not necessary for autotaxin to activate its receptor. Finally, when melanoma cells are treated with inhibitors of carbohydrate processing, such as N-methyl-1-deoxynojirimycin, 1-deoxymannojirimycin and swainsonine, they still secrete a motility-stimulating autotaxin. Therefore, the carbohydrate side chains on autotaxin are not necessary to stimulate motility; however, they may still play a role in folding, secretion or maintenance of the active Facile synthesis of the heptasaccharide repeating unit of O-deacetylated GXM of beta-D-Xylp-(1--2)-alpha-D-Manp-(1--3)-[beta-D-Xylp-(1--2)]-alpha-D-Manp-(1--3)-[beta-D-GlcpA-(1--2)][beta-D-Xylp-(1--4)]-alpha-D-Manp, the repeating unit of the exopolysaccharide from Cryptococcus neoformans serovar B, was synthesized as its methyl glycoside. Thus 2'-fucosyllactose -tri-O-benzoyl-beta-D-xylopyranosyl-(1--2)-3,4,6-tri-O-benzoyl-alpha-d-mannopyranosyl 2,3,4-tri-O-benzoyl-beta-D-xylopyranosyl-(1--2)-4,6-di-O-benzoyl-alpha-D-mannopyranoside simple transformation, were coupled to give a (1--3)-linked tetrasaccharide 9.

Deallylation of 9 followed by trichloroacetimidate formation produced the tetrasaccharide donor 11. Condensation of methyl 2,3,4-tri-O-benzoyl-beta-d-xylopyranosyl-(1--4)-2-O-acetyl-6-O-benzoyl-alpha-D-mannopyranoside . Coupling of with methyl 2,3,4-tri-O-acetyl-alpha-D-glucopyranosyluronate bromide (21) and subsequent deprotection furnished the target heptaoside. A alpha-D-Manp-(1--3)-[beta-D-Xylp-(1--2)]-alpha-D-Manp-(1--3)-[beta-D-GlcpA-(1--2)][beta-D-Xylp-(1--4)]-alpha-D-Manp, was also similarly synthesized as its methyl glycoside.Chemical stabilization of dispersed Escherichia coli for enhanced recovery with a handheld electroflotation system and detection by Loop-mediated Isothermal Manoa, Honolulu, Hawaii, United States of America.Constraints related to sample preparation are some of the primary obstacles to widespread deployment of molecular diagnostics for rapid detection of trace quantities (≤3 CFUmL) of food-borne pathogens. In this research, we report a sample preparation method using a novel handheld electroflotation system to concentrate and recover dilute quantities (2-3 CFUmL) of Escherichia coli detection by loop-mediated isothermal amplification (LAMP).

To protect suspended cells from shear stresses at bubble surfaces, a non-ionic surfactant cells and reduce their surface hydrophobicity. Effective conditions for recovery were determined through multifactorial experiments including various concentrations of Pluronic-F68 01,1,, 1 g L-1), chitosan oligosaccharide 1,, 1, g L-1), bacteria (2, 3, 4 CFUmL E. coli 25922), recovery times (, 15 and minutes), and degrees of turbulent gas flux (high and low).
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