Specificity of the Human Intestinal Disaccharidases
نویسنده
چکیده
The existence of several different a-glucosidases has recently been demonstrated in extracts of pig intestinal mucosa (1-7). These enzymes have varying specificity for disaccharides with a-D-glucopyranoside structure (e.g., maltose, sucrose, isomaltose, trehalose), and thus the intestinal hydrolysis of these sugars is caused by a more complicated enzyme mixture than had been previously believed (8, 9). The 8-glucosidase and /3-galactosidase activities of extracts of pig intestinal mucosa, in contrast, seem to be exerted by one enzyme, intestinal lactase (10, 11). It is not known whether the specificity of the human intestinal disaccharidases parallels that of the pig enzymes. This question is of clinical importance, however, since several cases of hereditary inability to digest certain disaccharides have been recently described, and are apparently caused by inherited deficiency of single intestinal disaccharidases (12-19). Since the human intestinal content, obtained by a catheter during the digestion of a meal, contains essentially no disaccharidases (20, 21), this material cannot be used for the study of the specificity of these enzymes. Therefore homogenates have been prepared of human intestinal mucosa, obtained from pieces of small intestine cut out during surgical operations. These homogenates had powerful disaccharidase activities, and the specificity of the enzymes responsible for these activities has been studied by heat inactivation.
منابع مشابه
Specificity of the human intestinal disaccharidases and implications for hereditary disaccharide intolerance.
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