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D. J. BELL
Heparin (157), the "mucoitin sulfuric acids" (158), and hyaluronic
acid (159) are based on D-glucosamine and D-glucuronic acid in equimolar proportions. Many plant gums (97) contain D-glucuronic acid
units. The acid has been isolated from hydrolysis products of polysaccharide material from brown algae where it occurs along with
D-mannuronic and L-guluronic acids (160). Green-algal polysaccharides
from Cladophora rupestris (106b), Ulva lactuca (160a), and Acrosiphonia centralis (Spongomorpha arcta) (160b) also yield D-glucuronic
acid as do certain fungal products (65a) and certain bacterial polysaccharides, (Chapter 8), blood group substances, and chondroitin Sulfate of animal connective tissue (161).
2. Ό-Galacturonic Acid
Like its glucose-derived isomer, D-galacturonic acid is found in
many natural situations, where it enters into the composition of polysaccharides. No simple glycosides comparable with the animal glucuronosides are known.
D-Galacturonic acid forms the building material of the "pectic acid"
fraction of pectin (162). A variable proportion of the carboxyl groups
are in the form of methyl esters, and it is believed that some of the
free hydroxyl groups are acetylated. With other sugars, it is found in
certain gums (97); it does not appear to have been detected in fungal
products (65a) although it comprises a major part of the capsular
polysaccharide of Pneumococcus type I.
3. "L-lduronic Acid and ^Guluronic Acid
Improved methods of analytical separation have led to the discovery
that L-iduronic acid units occur in "chondroitin sulfuric acid-B" (163)
or ß-heparin (164). L-Guluronic acid has been found to be a minor
component of alginic acid (see below) (160,165).
4. Ό-Mannuronic Acid
The acidic polysaccharide alginic acid, which is characteristic of
brown algae, is unique in being composed virtually entirely of units of
D-mannopyranuronic acid. Small amounts of L-guluronic acid are present
in some samples (165). As far as the writer is aware no other occurrence of D-mannuronic acid is known.
5. Ώ-Galactosaminuronic Acid (165a)
This substance is a component of the Vi-antigens of Escherichia
colt, Salmonella typhosa, and Paracolobactrum ballerup and is the first
natural aminohexuronic acid to be discovered.
D. J. BELL
Heparin (157), the "mucoitin sulfuric acids" (158), and hyaluronic
acid (159) are based on D-glucosamine and D-glucuronic acid in equimolar proportions. Many plant gums (97) contain D-glucuronic acid
units. The acid has been isolated from hydrolysis products of polysaccharide material from brown algae where it occurs along with
D-mannuronic and L-guluronic acids (160). Green-algal polysaccharides
from Cladophora rupestris (106b), Ulva lactuca (160a), and Acrosiphonia centralis (Spongomorpha arcta) (160b) also yield D-glucuronic
acid as do certain fungal products (65a) and certain bacterial polysaccharides, (Chapter 8), blood group substances, and chondroitin Sulfate of animal connective tissue (161).
2. Ό-Galacturonic Acid
Like its glucose-derived isomer, D-galacturonic acid is found in
many natural situations, where it enters into the composition of polysaccharides. No simple glycosides comparable with the animal glucuronosides are known.
D-Galacturonic acid forms the building material of the "pectic acid"
fraction of pectin (162). A variable proportion of the carboxyl groups
are in the form of methyl esters, and it is believed that some of the
free hydroxyl groups are acetylated. With other sugars, it is found in
certain gums (97); it does not appear to have been detected in fungal
products (65a) although it comprises a major part of the capsular
polysaccharide of Pneumococcus type I.
3. "L-lduronic Acid and ^Guluronic Acid
Improved methods of analytical separation have led to the discovery
that L-iduronic acid units occur in "chondroitin sulfuric acid-B" (163)
or ß-heparin (164). L-Guluronic acid has been found to be a minor
component of alginic acid (see below) (160,165).
4. Ό-Mannuronic Acid
The acidic polysaccharide alginic acid, which is characteristic of
brown algae, is unique in being composed virtually entirely of units of
D-mannopyranuronic acid. Small amounts of L-guluronic acid are present
in some samples (165). As far as the writer is aware no other occurrence of D-mannuronic acid is known.
5. Ώ-Galactosaminuronic Acid (165a)
This substance is a component of the Vi-antigens of Escherichia
colt, Salmonella typhosa, and Paracolobactrum ballerup and is the first
natural aminohexuronic acid to be discovered.