Monosaccharides periodate oxidations

In the spermatozoa of the sea urchin Anthocidaris crassipina, nine sialoglycolipids were found, two of which were isolated and their structures established from the results of acid hydrolysis, methylation, and periodate oxidation.139 The major component of the glycolipid mixture is a disialo-glycolipid, NeuAc-(2- 8)-NeuAc-(2- 6)-Glc-Cer. The least-polar, minor component has the structure of a monosialoglycolipid, NeuAc-(2 - 6)-Glc-Cer. In these compounds, glucose is again the only neutral monosaccharide, and the sialic acid is attached to it at 0-6. 

Preliminary examinations of dextran structures were conducted by optical rotation, infrared spectroscopy and periodate-oxidation reactions. More detailed results can be achieved by methylation analysis [19]. The hydroxyl groups are methylated with methyl iodide after activation with sodium methylsulfinyl carbanion (Fig. 2). The methyl dextran is hydrolysed to the corresponding different methylated monosaccharides, which are furthermore reduced and peracetylated. The resulting alditol acetates of methylated sugars are separated by gas chromatography and identified by their retention times. In particular, a combined capillary gas-liquid chromatography/mass... 

Chemical modifications of the antigens were achieved by oxidation of the monosaccharide residues with periodate and reduction of the carboxyl groups of the uronic acid residues by the carbodiimide and borohydride methods, Fig. (IOC). The periodate oxidation was performed by a procedure described in the literature [37]. The reduction of the uronic acid residues of the antigen was performed by the carbodiimide (CMC) and sodium borohydride method [38], The oxidized and reduced types of antigens no longer reacted with the antibodies, Fig. (IOC). 

Finally, Hirst s later contributions to monosaccharide chemistry must not be overlooked. With E. G. V. and Elizabeth Percival, four different trimethyl, 3,4- and 4,5-dimethyl, and the 4-methyl ethers of D-fructose were synthesized from isopropylidene derivatives having well established structures. Certain methyl ethers of D-mannuronic acid and D-glucuronic acid were also prepared, and their periodate oxidation was compared with that of related ethers of D-galacturonic acid. With Elizabeth Percival, he also contributed articles on the methyl ethers of mono- and di-saccharides, and on glycofuranosides from cyclic carbonates, to Methods in Carbohydrate Chemistry, Vol. 2 (1963). 

The monosaccharide composition of the products of the alkalii saponification of cellulose tosylates containing tosyloxy groups at Cg has been established on the basis of data obtained from a study of the composition of the products of acetylation, nitration, and periodate oxidation, and from quantitative paper chromatography of the products of complete hydrolysis of the mixed polysaccharides synthesized. The content of 3,6-anhydroglucose units in the 3,6-anhydro derivatives of cellulose was found to be 50-70 mol.-% (10-13). 

To jdeld a dialdehyde on periodate oxidation, a monosaccharide derivative must be held in a ring form by suitable substituents. The oxidation products can be divided into two classes those which generally do not contain hydroxyl groups elsewhere in the molecule, and form hemialdals, for example (3), and those which can form internal hemiacetals with a hydroxyl group elsewhere in the molecule, for example (4) the latter class... 

The structures of methyl /S-lactoside and methyl /3 cellobioside have been correlated, " in the same way as for monosaccharide glycosides, by periodate oxidation followed by reduction. Both compounds gave the same... 

With hexoses, except for their derived alditols, formaldehyde is produced from a glycosidically bound, nonreducing, furanosyl residue, but not from a similar pyranosyl residue. In the periodate oxidation of oligosaccharides composed of monosaccharide residues commonly occurring in the pyranoid form, the possibility of liberation of formaldehyde should always be checked. Thus, with a-n-glucopyranosyl a-D-galactofuranoside, the detection of nearly one mole of formaldehyde i>er mole, liberated early in the oxidation, was important evidence that the D-galactose residue occurs in the (unexpected) furanoid form. 

In the second procedure used to determine a monosaccharide s ring size, an acetal of the monosaccharide is oxidized with excess periodic acid. (Recall from Section 20.7 that periodic acid cleaves 1,2-diols.)... 

These difficulties may be overcome by the method of Johnson and Sieburth (1977), who combined several well-known reactions of carbohydrates to gain specificity in the determination. Their spectrophotometric assay included reduction of free monosaccharides to sugar alcohols with KBH4, periodate oxidation and subsequent determination of the liberated formaldehyde with 3-methyl-2-benzothia olinone hydrazone hydrochloride. Since only one compound is actually determined (formaldehyde), the problems associated with varying responses of different sugars are eliminated. 

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