A-Mannose

Streptomycin B (mannosidostreptomycin) has a mannose molecule attached to the methylglucosamine group, and is the first antibacterial product made, but is enzymatically converted to streptomycin later in the fermentation. 

Draw the structure of the disaccharide formed by two moles of a-mannose (see Question 19). 

Con A by the mannoside cluster at concentrations slightly above the nanomolar range, according to a mannose-dependent and partially reversible process. Finally, these results suggested that, rather than an increased avidity for Con A, the unusual potency of these molecular glycoasterisks was due to an efficient and kinetically controlled macromolecular assembly that strongly amplified the effect of these low-valency ligands. 

Attempts at 4-exo nucleophilic cyclization failed, presumably because of a heterolytic fragmentation of the intermediate radical cation (Scheme 32) [139], not unlike that proposed (Scheme 15) for the decomposition of a mannose-derived alkene radical cation. 

The branched cyclodextrins (CDs, 17 a, 17 b) and their analogues with D-galactosyl and a-D-mannosyl residues (17c, 17d) have also been prepared under mild conditions by the approach depicted in Scheme 6 [24,25]. Selective in situ S-deacetylation and activation was obtained by treatment of peracetylated 1-thioglycoses (10a, 8e, 8g) by cysteamine in the presence of diAioerythritol in HMPA [26]. This method was very efficient for ffie synthesis of branched CDs (17a) (80%), (17b) (60%), and (17c) (85%) when the acceptor molecule (15b) bearing primary iodide was used. However, peracetylated 1-thioa-D-mannose (8f) failed as a donor under these conditions, but tetra-O-acetyl-l-thio-a-mannose (8 b) afforded the expected CD (17d) in high yield (83%). 

Naturally occurring C-glycopeptides have recently been discovered. A C-linked a-mannose, where the mannopyranosyl Cl atom is directly linked to the C2 atom in a Trp indole ring, has been identified in humans 435 38 and in nonhuman organisms)525 Stereo-controlled synthesis of a-C-mannosyltryptophan has been reported)439,440,526,527 ... 

A mannose-containing cerebroside was found here (for the first time), and this extends the number of cerebrosides known today. An overwhelming majority of the cerebrosides in animals contain glucose or galactose70-266 the salt glands of the herring gull were, however, found to contain a xylosylceramide,267 and from a human adenocarcinoma, a fucosylceramide has been isolated.268... 

Figure 13. Plot of total ion current vj. emitter current for (A) mannose-1-phosphate, (B) mannose (OAc),rl-phosphate, and (C) mannose (OAc),-l-phosphate-O-...

Avrameas, A., Me.Ilroy, D., Hosmalin, A., Autran, B., Debre, P., Monsigny, M. etal. (1996) Expression of a mannose/ fucose membrane lectin on human dendritic cells. Eur. J. Immunol, 26, 394 100. 

Figure 1. Mutagenicity of the browned solutions from varying sugars and Lys. Key A, fructose , glucose O, galactose A, mannose , arabinose and ,...

S Omura, El Tomoda, N Tabata, Y Ohyama, A Abe, M Namikoshi. Roselipins, novel fungal metabolites having a highly methylated fatty acid modified with a mannose and an arabinitol. J Antibiot 52 586-589, 1999. 

Lysosomal proteins are targeted to the lysosomes via the addition of a mannose 6-phosphate signal that is added in the ds-compartment of the Golgi and is recognized by a receptor protein in the frans-compartment of the Golgi. The protein is then transported by specialized vesicles to a late endosome that later matures into a lysosome. The mannose 6-phosphate receptor recycles back to the Golgi for re-use. 

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