Hyalobiouronic acid

A common example that has been isolated from many plant polysaccharides is 2-0-(4-0-methyl-a-D-glucopyranosyluronic acid-D-xylose (64). Hyalobiouronic acid, [2-amino-2-deoxy-3-0-(/f-D-glucopyranosyluronic acid)-D-glucose] (65), whose A-acetyl derivative is the repeating unit of... 

Disaccharides of the hexuronic acid-hexosamine type constitute the fundamental repeating unit of many mucopolysaccharides, from which they are derived by hydrolytic degradation. Further hydrolytic treatment results generally in destruction of the uronic acid moiety of the disaccharide. Structural studies have been made on the disaccharides from hyaluronic acid (hyalobiouronic acid), chondroitinsulfate (chondrosine), and heparin (heparosine). 

The structure of hyaluronic acid is now well established. Acidic hydrolysis yields the constituent disaccharide, hyalobiouronic acid, whose structure was shown to be 2-amino-2-deoxy-3-0-(P-D-glucopyranosylu-ronic acid)-D-glucose by degradative studies (W3) and, more recently, by constitutional syntheses (J7, Tl). The hexosaminidic linkage has been shown to have a pi- 4 configuration by enzyme (W4) and methylation (Hll) studies, so that hyaluronic acid may be assigned structure (1). 

Since the hyalobiouronic acid can be obtained both by combined enzymic and acid hydrolysis and by direct acid hydrolysis alone, it is considered... 

Fig. 1.—Reaction Sequence in Determining the Structure of Hyalobiouronic Acid.

The Morgan-Elson reaction for the determination of 2-acetamido sugars can be used for obtaining an indication of the position of the glycosidic links in 2-acetamido-2-deoxy-D-glucose oligosaccharides. It has been used in this way to show the presence of (1 6) links and (1— 4) links Hyalobiouronic acid was ultimately converted to a neutral... 

Amino-2-deoxy-3-0-(/3-D-glucopyranosyluronic acid)-D-glucose (Hyalobiouronic acid) B 126... 

Hyalobiouronic acid, isolated from the mucopolysaccharide hyaluronic acid, contains glucosamine unit, and has been identified as 3-0-(jS-D-... 

Hyalobiouronic acid, 3-0-( -D-glucopyranosyl uronic acid)-2-amino-2-deoxy-D-glucose, can be obtained by the acid hydrolysis of hyaluronic add in a yield of about 60%. This result indicates that the disaccharide is a repeating unit of the polysaccharide . The structure of the disaccharide (I) was established as follows. The methyl ester of the disaccharide (II) was oxidized by mercuric oxide to the 2-amino-2-deoxy-gluconic acid derivative... 

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