The amino acid composition and quantitative sugar-amino acid relationships in sequential Smith-degradation products from Acacia polyacantha gum
Titel:
The amino acid composition and quantitative sugar-amino acid relationships in sequential Smith-degradation products from Acacia polyacantha gum
Auteur:
Anderson, D. M. W.
Verschenen in:
Food additives and contaminants. Pt. A, Chemistry, analysis, control, exposure & risk assessment
Paginering:
Jaargang 3 (1986) nr. 2 pagina's 123-132
Jaar:
1986-04
Inhoud:
Data are presented for the amino acid composition of Acacia polyacantha gum (0.37% N) and four sequential Smith-degradation (SD) products (0.72, 0.66, 0.72 and 1.0% N respectively). The molar polysaccharide/protein ratio in the gum (28:1) decreased to 9:1 in its fourth degradation product, which is a proteinaceous branched galactan; proline, hydroxyproline, aspartic acid, serine, threonine and leucine account for 80% of its amino acids. The first and fourth degradations eliminated large amounts of sugars but only small amounts of amino acids (molar ratios 112:1 and 75:1 for SD I and SD IV respectively). The second and third degradations eliminated higher molar proportions of amino acids together with all of the arabinose, rhamnose and uronic acids, and some of the galactose originally present (molar ratios for the sugars/amino acids eliminated= 14:1 and 16:1 for SD II and SD III respectively). Overall (four stages), 96.5% of the original polysaccharide but only 89% of the protein was eliminated. The proteinaceous enrichment of the galactan core largely involved proline, serine and threonine, but hydroxyproline and aspartic acid account for c. 30% of the amino acid content of the whole gum and each degradation product. An insight into the locations of proteinaceous material within the complex molecular structure of the gum has been gained.
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