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The impact of human IgE glycosylation on structure, function and disease mechanisms is not fully elucidated, and heterogeneity in different studies renders drawing conclusions challenging. Previous reviews discussed IgE glycosylation focusing on specific topics such as health versus disease, FcεR binding or impact on function. We present the first systematic review of human IgE glycosylation conducted utilizing the PRISMA guidelines. We sought to define the current consensus concerning the roles of glycosylation on structure, biology and disease. Despite diverse analytical methodologies, source, expression systems and the sparsity of data on IgE antibodies from non‐allergic individuals, collectively evidence suggests differential glycosylation profiles, particularly in allergic diseases compared with healthy states, and indicates functional impact, and contributions to IgE‐mediated hypersensitivities and atopic diseases. Beyond allergic diseases, dysregulated terminal glycan structures, including sialic acid, may regulate IgE metabolism. Glycan sites such as N394 may contribute to stabilizing IgE structure, with alterations in these glycans likely influencing both structure and IgE‐FcεR interactions. This systematic review therefore highlights critical IgE glycosylation attributes in health and disease that may be exploitable for therapeutic intervention, and the need for novel analytics to explore pertinent research avenues. [ABSTRACT FROM AUTHOR]

Fluorescence microscopy has revealed that the phospholipid cardiolipin (CL) and FlAsH-labeled transporters ProP and LacY are concentrated at the poles of Escherichia coli cells. The proportion of CL among E. coli phospholipids can be varied in vivo as it is decreased by cls mutations and it increases with the osmolality of the growth medium. In this report we compare the localization of CL, ProP, and LacY with that of other cytoplasmic membrane proteins. The proportion of cells in which FlAsH-labeled membrane proteins were concentrated at the cell poles was determined as a function of protein expression level and CL content. Each tagged protein was expressed from a pBAD24-derived plasmid; tagged ProP was also expressed from the chromosome. The osmosensory transporter ProP and the mechanosensitive channel MscS concentrated at the poles at frequencies correlated with the cellular CL content. The lactose transporter LacY was found at the poles at a high and CL-independent frequency. ProW (a component of the osmoregulatory transporter ProU), AqpZ (an aquaporin), and MscL (a mechanosensitive channel) were concentrated at the poles in a minority of cells, and this polar localization was CL independent. The frequency of polar localization was independent of induction (at arabinose concentrations up to 1 mM) for proteins encoded by pBAD24-derived plasmids. Complementation studies showed that ProW, AqpZ, MscS, and MscL remained functional after introduction of the FlAsH tag (CCPGCC). These data suggest that CL-dependent polar localization in E. coli cells is not a general characteristic of transporters, channels, or osmoregulatory proteins. Polar localization can be frequent and CL independent (as observed for LacY), frequent and CL dependent (as observed for ProP and MscS), or infrequent (as observed for AqpZ, ProW, and MscL). doi: 10.1128/JB.00967-09

An assessment of the relative reactivities of the 4-OH of N-acetylglucosamine acceptors bearing simple protecting groups, [beta]-linked or [alpha]-linked D or L sugars at O-3 is described by using a per-O-acetylated [alpha]-D-glucosyl trichloroacetimidate donor under activation by B[F.sub.3].O[Et.sub.2]. The analysis has showed that the acceptor has undergone glycosylation but a decrease in the absorbance peak corresponding to the trisaccharide along with the appearance of a peak corresponding to a perbenzylated fucose hemiacetal has shown that the trisaccharide product is unstable in the reaction conditions.

The glycosylation of N-acetylglucosamine acceptors at O-4 was employed to understand the scope and application of the temporary conversion of N-acetyl groups to alkyl imidates. One-pot glycosylation reactions via alkyl imidate protected acceptor intermediates is reported.

The carbohydrate antigen dimeric Lewis X (DimLe x ), which accumulates in colonic and liver adenocarcinomas, is a valuable target to develop anti-cancer therapeutics. Using the native DimLe x antigen as a vaccine would elicit an autoimmune response against the Le x antigen found on normal, healthy cells. Thus, we aim to study the immunogenic potential of DimLe x and search internal epitopes displayed by DimLe x that remain to be recognized by anti-DimLe x monoclonal antibodies (mAbs) but no longer possess epitopes recognized by anti-Le x mAbs. In this context, we attempted to map the epitope recognized by anti-DimLe x mAb SH2 by titrations and competitive inhibition experiments using oligosaccharide fragments of DimLe x as well as Le x analogues. We compare our results with that reported for anti-Le x mAb SH1 and anti-polymeric Le x mAbs 1G5F6 and 291-2G3-A. While SH1 recognizes an epitope localized to the non-reducing end Le x trisaccharide, SH2, 1G5F6, and 291-2G3-A have greater affinity for DimLe x conjugates than for Le x conjugates. We show, however, that the Le x trisaccharide is still an important recognition element for SH2, which (like 1G5F6 and 291-2G3-A) makes contacts with all three sugar units of Le x . In contrast to mAb SH1, anti-polymeric Le x mAbs make contact with the Glc N Ac acetamido group, suggesting that epitopes extend further from the non-reducing end Le x . Results with SH2 show that this epitope is only recognized when DimLe x is presented by glycoconjugates. We have reported that DimLe x adopts two conformations around the β-d-Glc N Ac-(1→3)-d-Gal bond connecting the Le x trisaccharides. We propose that only one of these conformations is recognized by SH2 and that this conformation is favored when the hexasaccharide is presented as part of a glycoconjugate such as DimLe x -bovine serum albumin (DimLe x -BSA). Proper presentation of the oligosaccharide candidate via conjugation to a protein or lipid is essential for the design of an anti-cancer vaccine or immunotherapeutic based on DimLe x .