Mannose 2-acetamido-2-deoxy

At present, little is known about the biosynthesis of the D-mannose-(2-acetamido-2-deoxy-D-glucose) type of chain and of the core ... 

The polysaccharide chain of the cell wall lipopolysaccharide of Escherichia coli 058 contains D-mannose, 2-acetamido-2-deoxy-D-mannose, 3-0-[(l R)-carboxyethyl)]-L-rhamnose (rhamnolytic acid), and 0-acetyl groups in the molar ratios of 2 1 1 . Structural investigations show that this polysaccharide, which contains a substituted trisaccharide repeating unit, has an identical structure (4) to that of Shigella dysenteriae type 5. 

Solubilized surface proteins from normal human lymphocytes have been obtained by mild digestion with trypsin, and the binding of these components to labelled Ricinus sanguineus has been studied.A method for the direct visualization of lymphocyte membrane receptors has made use of fluoresceinyl derivatives of glycosylated cytochemical markers such as bovine serum albumin covalently attached to either D-mannose, 2-acetamido-2-deoxy-D-galactose, L-fucose, or lactose. 

The carbohydrate composition of human placental 3-D-2-acetamido-2-deoxy-hexosidases A, B, and heat-converted B was determined by g.l.c. Similar quantities of D-mannose, 2-acetamido-2-deoxy-D-glucose, and D-galactose are present in the A and B isoenzymes, whereas 7V-acetylneuraminic acid is found in s nificant amount in only the A isoenzyme.The heat-converted -D-acetamido-2-deoxy-hexosidase B also contains only trace amounts of A-acetylneuraminic acid, but is about 1.5-fold richer in D-mannose and 2-acetamido-2-deoxy-D-glucose, and nearly two-fold richer in D-galactose than native 3-D-2-acetamido-2-deoxy-hexosidase B. Since native and converted B are thought to be composed of four identical protein chains, these results suggest that there may be variable glycosylation of these chains. 

Human anti-thrombin III contains residues of D-galactose, D-mannose, 2-acetamido-2-deoxy-D-glucose, and neuraminic acid. The neuraminic acid residues do not appear to be required for the inhibitory action of this glycoprotein on thrombin, and therefore their presence in the glycoprotein may delay the clearance of the glycoprotein from the bloodstream, as has been shown for ceruloplasmin and ai-acid glycoprotein. 

Free monosaccharides can be used for direct glycosylation of Spheron , a spherical macroporous hydroxyalkyl methacrylate-ethylene dimethacrylate co-polymer. Derivatives of L-fucose, o-galactose, D-glucose, D-mannose, 2-acetamido-2-deoxy-D-galactose, and 2-acetamido-2-deoxy-D-glucose have been prepared in this way and shown to be efficient affinity carriers for the isolation of a number of lectins. 

A method based on inhibition of agglutination has been used to differentiate serologically between Brucella abortus and Yersinia enterocolitica. An antigen isolated from B. abortus consists of protein, phosphoglyceride (but no lipid A), and a polysaccharide containing residues of D-glucose, D-mannose, 2-acetamido-2-deoxy-D-glucose, and 3-deoxy-2-octulosonic acid. 

Miscellaneous.—ewcto-j3-D-2-Acetamido-2-deoxyglucanase H from Streptomyces griseus completely hydrolysed the unit A (D-mannose -> 2-acetamido-2-deoxy-D-glucose) glycopeptides of thyroglobulin, but did not act on a modified unit B (a complex heteropolysaccharide) free from side-chains. This and other evidence indicated that this enzyme and an eni/o-/8-D-2-acetamido-2-deoxy-glucanase D from Diplococcus pneumoniae have different specificities the... 

As 2-amino-2-deoxy-D-mannose is tumorstatic and 2-acetamido-2-deoxy-D-mannose 6-phosphate is an obligatory intermediate in the biosynthetic pathway to sialic acid, displacement of the essential OH-6 with a fluorine atom should be interesting from the biological viewpoint. 2-Acetamido-1,3,4-tri-0-acetyl-2,6-dideoxy-6-fluoro-D-mannopyranose (see Table 111 in Section 11,3) and its O- and A,0-deacetyl derivatives were prepared the first compound showed weak anticancer activity. 

The biosynthesis of Kdo and neuraminic acid is known to involve enol-pyruvate phosphate and D-arabinose or 2-acetamido-2-deoxy-D-mannose, respectively. Nothing is known about the biosynthesis of all the other glycu-losonic acids. One interesting problem is, for example, whether the two 5,7-diamino-3,5,7,9-tetradeoxynonulosonic acids are synthesized analogously to neuraminic acid, from a three- and a six-carbon fragment, by modification of neuraminic acid on the sugar nucleotide level, or by a third, less obvious route. 

Following the synthesis by Comforth and his associates18 of NeuAc from oxalacetate and 2-acetamido-2-deoxy-D-mannose, Ghalambor and Heath29,31 prepared KDO (isolated as the crystalline methyl 2,4,5,7,8-penta-0-acetyl-3-deoxy-D-manno-2-octulopyranosonate, 70) from D-arabinose and oxalacetate by an analogous reaction (see Scheme 20). 

Several model investigations directed toward the analysis of glycoproteins have used methanolysis, and one of the first such model studies was the article by Clamp, Dawson, and Hough86 and their two earlier communications.364,365 These authors examined mixtures containing D-galactose, D-mannose, L-fucose, 2-acetamido-2-deoxy-D-glucose, and neuraminic acid. The solution, after methanolysis, was... 

Inversion of the acetamido group at C-2", with simultaneous hydrolysis of the glycosyl linkage, occurs when uridine 5 -(2-acetamido-2-deoxy-a-D-glucopyranosyl pyrophosphate) (34) is treated with a rat-liver enzyme.411,412 The products are uridine 5 -pyrophosphate (6) and 2-acetamido-2-deoxy-D-mannose (101), and they are also formed from uridine 5 -(2-acetamido-2-deoxy-a-D-mannopyranosyl pyrophos-... 

The first evidence for the presence of an a-D-mannosyl link in ovalbumin glycopeptides was provided by the action of almond emulsin,101,102 although the absence of /3-D-mannosidase from the enzyme preparation was not confirmed until later.103 The presence of 2-acetamido-2-deoxy-/M>glucosidase in emulsin left doubt as to the terminal position of all of the D-mannose released. 

When the ovalbumin was incubated with purified, jack-bean a-D-mannosidase, at least two molecules of D-mannose per molecule were released, suggesting that these residues are a-D-linked in a terminal position. Two glycopeptides having different contents of hexosamine were subjected to the action of purified 2-acetamido-2-deoxy-/ -D-glucosidase, and, in each case, two hexosamine residues per molecule were either inaccessible, or resistant to attack by the enzyme. 

Results of an experiment with an oligosaccharide free from amino acid were less conclusive, but were not incompatible with the structure shown. The oligosaccharide was prepared from a separated glycoprotein fraction having a D-mannose hexosamine ratio of 5 3. a-D-Mannosidase and 2-acetamido-2-deoxy-/3-D-glucosidase were used alternately. Initially, a-D-mannosidase removed about 1.5 D-mannose residues per molecule. Subsequent treatment of the residual oligosaccharide with 2-acetamido-2-deoxy-/3-D-glucosidase released rather less than one proportion of hexosamine residue, and then another 1.5 residues of D-mannose became open to attack by a-D-mannosidase. 

After removal of all of the D-mannose, one more hexosamine residue could be hydrolyzed off by 2-acetamido-2-deoxy-/3-D-glucosidase, indicating that this residue, also, is /3-D-linked.73... 

The synthesis of a 9-azido-9-deoxy derivative of Neu5Ac, namely, 5-acetamido-9-azido-3,5,9-trideoxy-D-gh/cero-D-ga/acto -2-nomdo-pyranosonic acid, from enolpyruvate phosphate and 2-acetamido-6-azido-2,6-dideoxy-D-mannose, using Neu5Ac synthase from A. meningitidis, has been reported.225... 

In contrast to this work on whole brain, Kemp and Stoolmiller138 used cultured mouse-neuroblastoma cells for their study of incorporation of [ lH]2-acetamido-2-deox> -D-mannose into the sialic acid moiety of gangliosides. They were able to demonstrate clearly the precursor-product relationship among CMS, GM2, and GM1. They found that cultured NB41A cells incorporated [3H]2-acetamido-2-deoxy-D-man-nose into the sialic acid moiety of GM3 in less than 10 minutes. Labeled GM2 was not detected in cells incubated for less than 30 minutes, and measurable activity did not appear in G I1 until alter 60 to 90 minutes. These results further supported the concept that the pathway of synthesis of ganglio-tvpe gangliosides proceeds by way of GM3 —> GM2 — GM1. 

An anti-2-acetamido-2-deoxy-D-mannose immunoglobulin, MOPC 406, is an IgA that binds73 polysaccharides from Salmonella weslaco and Escherichia coli 031. These polysaccharides are known to contain 2-acetamido-2-deoxy-D-mannose,83 and it has been shown that the specificity of this protein is directed towards /3-D-linked 2-acetamido-2-deoxy-D-mannopyranosyl residues.84 Inhibition studies revealed that the apparent affinity of the methyl /3-D-glycoside for the combining region of MOPC 406 is high. 

A polyisoprenyl phosphate has been shown to act as an acceptor for D-mannose and 2-acetamido-2-deoxy-D-glucose in mung beans347 and peas.348 Similar polyisoprenyl phosphates that accept glycosyl groups have been reported in soy bean, wheat germ, and pea seedlings,349 Pha-... 

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