カキ・グリコーゲンの酵素消化について

抄録

In a series of studies on oyster glycogen, we elucidated its detailed structural features. In the nutritional view, the present investigation has been concerned with the enzymic degradation of the highly branched glycogen in the digestive tracts, compared with the case of starch.

The purified glycogen and amylopectin (waxy maze starch) were degraded by salivary α-amylase (human: crystallized), giving α-amylolysis limit, 48.3% and 57.8%, respectively.

The maltosaccharides produced by the amylase action were fractionated by HPAEC (Dionex), and each branched oligosaccharide collected from the column was characterized by analysis of the saccharides released by action with α-glucosidase, isomaltase or pullulanase. In this way, the following branched oligo saccharides were identified: 6³-α-glucosyl-maltotriose and -maltotetraose, 6³-α-maltosyl-maltotrioseand maltotetraose, 6³-α-maltotriosyl-maltotrioseand -maltotetraose, in addition to several unidentified branched maltosaccharides. These branched dextrins, compared with those in amylopectin. supporting multi ply branched structure of the glycogen.

Following the salivary amylolysis, glycogen was further degraded by pancreatic α-amylase (hog: crystallized), and finally by rat intestinal glucosidases (acetone powder; Sigma Co.), and on each step the released oligosaccharides were analyzed by HP AEC. The results showed that by successive actions with salivary and pancreatic amylase the oyster glycogen was gradually hydrolyzed to give mainly maltose and branched α-limit dextrins. Although these oligosaccharides were finally hydrolyzed to glucose by intestinal α-glucosidases (hydrolysis, 86% as glucose), small amounts of multiply branched oligosaccharides might still remain as the glucosidase-resistant forms.