Monosaccharides enzymic digestion

The enzymic digestion of an adenosine diphosphate sugar fraction from larch wood leads, among other monosaccharide products, to a fructose.20 This result suggests the occurrence of a corresponding fructosyl ester, but its structure remains undetermined. 

The intestinal oligo- and disaccharidases are fixed components of the cell membrane of the brush border region of the wall of the small intestine. These enzymes digest dietary carbohydrate to monosaccharides which are absorbed through the intestinal wall. They include sucrase, maltase, isomaltase, lactase, trehalase, and hetero-p-glucosidase. In the late 1970s, it was realized that inhibition of all or some of these activities could regulate the absorption of carbohydrate, and that these inhibitors could... 

Source and kinds of disaccharidases The final digestive processes occur at the mucosal lining of the small intestine. Several disaccharidases [for example, lactase (p-galactosidase), sucrase, maltase, and isomal-tase] produce monosaccharides (glucose, galactose, and fructose). These enzymes are secreted by and remain associated with the luminal side of the brush border membranes of intestinal mucosal cells. Absorption of the monosaccharides requires specific trans porters. 

Pancreatic amylase hydrolyses starches to maltose and oligosaccharides. Final digestion of carbohydrates takes place in the brush border of the epithelial cells. Oligosaccharides are hydrolysed to monosaccharides and reabsorbed. Proteins are hydrolysed to peptides by pepsin, trypsin and several other proteolytic enzymes from the pancreas. The brush border attaches proteases which hydrolyse the di- and tripeptides to amino acids and absorbs them. 

The expected products of a hexosaminidase digest of structure 1 would be FucMan3GlcNAc2 and the released monosaccharide, N-acetylglucosamine. Treatment of the PNGase F digest of MAb MY9-6 with the Jack bean enzyme (Fig, 2F) resulted in complete disappearance of Peak 1. A new peak with a retention time identical to a FucMan3GlcNAc2 standard (between 9 and 10 min) was observed (Fig. 2D). Additionally, a peak seen at 5 min. upon hexosaminidase treatment, presumably represents the released GlcNAc (Fig. 2F). 

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