Carbohydrates and Proteins
The neem gum exudate from the stem was found to be a very complex condensate of
proteins and heteropolysaccharides. The proteins are linked very tightly to the
polysaccharides, which constitute the major components. The nature of these complexes
hampers the total elucidation of the structure of the gum. The material is well protected
against enzymatic attack and the usual chemical or physical techniques applied to separate
the proteins from the polysaccharide matrix are not very successfull.107. A variety of smaller
gum components, however, have been identified after more drastic degradation methods.
D-glucose, D-glucuronic acid, L-arabinose, L-fucose,I02 mannose, xylose, rhamnose, I
D-glucosamine,81 the aldobiouronic acids,16 4-0-(4-0-methyl-a¬D-glucopyranosyl uronic
acid)-D-galactose and 4-0-(a-D-glucopyranosyl uronic acid)-D¬galactose I and aldotriouronic
acidsl6 were reported. The amino acid composition of the gum was investigated 1.2. The
most abundant amino acid was aspartic acid, while considerable amounts of serine and
threonine were also found. A glycopeptide from the gum after pronase digestion had
molecular weight of about 2000 D. The carbohydrate moiety consisted of arabinose,
galactose and glucosamine in a molar ratio of 2.96:2.0:4.9. The protein part (about 40 weight
per cent) was composed of eight different amino acids 107.
The neem gum exudate from the stem was found to be a very complex condensate of
proteins and heteropolysaccharides. The proteins are linked very tightly to the
polysaccharides, which constitute the major components. The nature of these complexes
hampers the total elucidation of the structure of the gum. The material is well protected
against enzymatic attack and the usual chemical or physical techniques applied to separate
the proteins from the polysaccharide matrix are not very successfull.107. A variety of smaller
gum components, however, have been identified after more drastic degradation methods.
D-glucose, D-glucuronic acid, L-arabinose, L-fucose,I02 mannose, xylose, rhamnose, I
D-glucosamine,81 the aldobiouronic acids,16 4-0-(4-0-methyl-a¬D-glucopyranosyl uronic
acid)-D-galactose and 4-0-(a-D-glucopyranosyl uronic acid)-D¬galactose I and aldotriouronic
acidsl6 were reported. The amino acid composition of the gum was investigated 1.2. The
most abundant amino acid was aspartic acid, while considerable amounts of serine and
threonine were also found. A glycopeptide from the gum after pronase digestion had
molecular weight of about 2000 D. The carbohydrate moiety consisted of arabinose,
galactose and glucosamine in a molar ratio of 2.96:2.0:4.9. The protein part (about 40 weight
per cent) was composed of eight different amino acids 107.
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