Monosaccharide moieties

In this context, Lindhorst et al. proposed biological investigations of pentaerythri-tol-based mannoside clusters to test their capacity to block the binding of E. coli to yeast mannan in vitro.75 In all of the proposed structures, and according to a rational approach, pentaerythritol itself, as well as the included C3 spacers, were used as structural components for substituting the inner regions of the monosaccharide moieties (Scheme 4). The tetravalent cluster 27 has been efficiently synthesized according... 

Fig. 4.5.4 Identification of mutations in the transferrin protein by neuraminidase treatment. Unusual patterns in the IEF of serum transferrin might lead to pitfalls in CDG diagnostics. These varying patterns are often due to mutations of charged amino acids in the protein backbone of the transferrin molecule, which might lead, for example, to an accumulation of trisialo transferrin bands (lane 3, indicated by a question mark). Further investigations are carried out by cleaving off charged sialic acid monosaccharide moieties from transferrin-linked oligosaccharides by neuraminidase treatment, followed by IEF and transferrin antibody staining. In the case of protein mutations, additional bands below (lane 4) or above (not shown) the desialylated transferrin form appear...

A very useful source on various NMR techniques and chemical shifts of functionalized carbon atoms that contains tabulated data on monosaccharides is Reference [23]. Specifically correlating functional groups with chemical shifts of protons and the associated carbon is an important tool for elucidating the stmcture of the monosaccharide moiety of many complex oligosaccharides. Since monosaccharides contain one or more chiral centers, absolute configuration must be known in order to predict the conformational shape of the molecules. The outcome of many stereoselective functionalizations of free and partially functionalized monosaccharides depends on conformation. 

The above methodology proved very successful for accessing pure standards of DFAs 5, 7, 10, and 14, which are among the most abundant DFAs in kinetic mixtures of diastereomers as well as in caramel. It is, however, intrinsically limited to compounds having identical ring size at both monosaccharide moieties. Moreover, the di-p-D-fructofuranose l,2 2,l -dianhydride isomer 12 remained elusive. 

Even so, it has been concluded that there is a structure-activity relationship between the different PPGs. There is a direct relationship between the antioxidant activity and the number of hydroxyl groups, and an inverse relationship with the increasing of higher monosaccharides moieties. 

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