D-Galactose 6-sulfate

Chrondus crispus Ceramium rvbrum Delassaria sanguinea D-galactose, sulfate and 108... 

Some 2-acetamido-2-deoxy-D-galactose residues do not become sulfated, and some of them accept two sulfate groups. Although a 2-acetamido-2-deoxy-D-galactose sulfate can be isolated in relatively large amounts from hen oviduct,358 it is unlikely to be a direct pre-... 

D-Galactose phenylosotriazole, III, 38 a-D-Galactose 1-phosphate, V, 71 D-Galactose sulfates, II, 178 aldehydo-D-Galactose, l-chloro-l-thio-ethoxy-, pentaacetate, I, 96 aMelij/do-D-Galactose, l-thioethoxy-3,4,-6,6-tetraacetyI-, ethyl 1,2-orthoacetate, I, 96, 121... 

Scheme 9. Possible routes of intramolecular desulfation of isomeric (1 — 4)-linked D-galactose sulfates under basic conditions.

A group of seaweed extracts, c. is constituted from sulfated galactan polysaccharides of different repeating units, such as D-galactose-sulfate and 3,6-anhydro-D-galactose-sulfate. 

D-galactose-4-sulfate—3,6-anhydro-D-galactose-2-sulfate (see Carbohydrates). 

It will be appropriate to consider first the building units of the carbohydrate residues and it will be immediately apparent that D-mannose and D-galactose with N-acetyl-amino sugars and hexuronic acids play a predominant role. It is proposed, therefore, to discuss briefly some of the more important discoveries connected with the two latter groups and with the carbohydrate sulfates. 

A mixture of 10 g. of D-galactose, 10 ml. of ethyl acetoaeetate, 10 ml. of ethanol, and 5 g. of zinc chloride is heated on a steam bath during 75 minutes. The mixture is cooled, 45 ml. of water is added, and the solution is extracted with two 30-ml. portions of benzene. The aqueous layer is then extracted with nine 15-ml. portions of ethyl acetate. The united extracts are washed successively with an aqueous solution of sodium bisulfite and with an aqueous solution of sodium bicarbonate, dried with anhydrous sodium sulfate, filtered, and the filtrate evaporated to dryness, affording 4.5 g. of a sirup. This is saponified with 12.5 ml. of 10% sodium hydroxide solution, and then acidified (to Congo Red) with phosphoric acid. The aqueous solution is extracted with successive 30-ml. portions of ethyl acetate, and these are dried with anhydrous sodium sulfate, and individually evaporated to dryness. Extracts after the fourth yield a solid product m. p., 130°. Recrystallized from petroleum ether plus acetic acid, the compound has m. p. 132-134° yield, variable, ca. 2%.54... 

The molecules are helices having a twofold screw-axis, with an axial rise per disaccharide residue of 9.45 A (945 pm). The axes of the chains are parallel, and about equally spaced, but are not further organized into crystalline arrays. A hydrogen bond was proposed between the OH-3 group of the 2-acetamido-2-deoxy-D-glucose residues and 0-5 of the D-galactose 6-sulfate residues. 

As indicated later (see Section VI,8), on addition of the chloride of praseodymium, europium, or other lanthanides to mono- or poly-sac-charide phosphates in D20, the signals of carbon atoms substituted with phosphate groups are recognizable, as they are displaced, relative to the rest of the 13C-n.m.r. spectrum.155 However, this diagnostic method is not applicable to sulfated polysaccharides, as signal displacements were not observed on addition of praseodymium or europium chloride to a solution of a,/3-D-galactose 6-sulfate or its sodium salt.156... 

More drastic hydrolysis of gum arabic has led to the isolation of 3-D-galactopyranosyl-D-galactose (XVII), the structure of which was ascertained by the fact that treatment of it with methyl sulfate gave the octamethyl derivative (XVIII), which upon hydrolysis afforded 2,3,4,6-tetramethyl-D-galactose (XI) and 2,4,6-trimethyl-D-galactose (XIX). ... 

Gelidium pacificum Okam. Chrondus ocellatus Holmes D-galactose D-galactose, methyl pentose, 2-keto-hexonic acid (7), sulfate, D- and irerythrose 111... 

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