Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Castanospermine (CS) is a potent but non-selective inhibitor of many glycohydrolases including the intestinal disaccharidases. Several CS-glucosides were synthesized to investigate the effect of an attached glucopyranosyl residue on the potency and selectivity of CS toward inhibition of intestinal disaccharidases. 8 alpha-glucosyl-CS and 7 alpha-glucosyl-CS were nearly as potent against sucrase activity as CS (IC50 values = 30, 40, and 20 nM respectively) but were 1/50 or less as potent as CS against lactase and trehalase activities. 8 beta-glucosyl-CS was 1/20 to 1/140 as potent as CS and 1 alpha-glucosyl-CS was 1/57 to 1/1500 as potent as CS against disaccharidase activities. 1 alpha-glc-CS was less selective than CS, whereas the other CS-glucosides were more selective. 7 alpha-glc-CS and 8 alpha-glc-CS were the most sucrase selective and were particularly ineffective against trehalase and lactase activities. 8 beta-glc-CS was similar to CS except for relatively weaker trehalase inhibition. In summary, selectivity toward certain disaccharidases was achieved by glucosylation of CS hydroxyls. However, a simple structural comparison of the CS-glucoside to a disaccharide substrate did not reliably predict which disaccharidase would be more inhibited by the CS-glucoside.
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PMID:Castanospermine-glucosides as selective disaccharidase inhibitors. 233 10

In a retrospective study, jejunal mucosal disaccharidase and alkaline phosphatase activities have been investigated in 40 controls and patients with proven celiac sprue (n = 26), lactase deficiency (n = 26), osteoporosis or osteomalacia (n = 16), chronic pancreatitis (n = 12), giardiasis (n = 7), or Crohn's disease (n = 7). Apart from a nonselective reduction of mucosal enzyme activities in the sprue syndrome and a selective reduction of lactase activity in the patients with primary lactase deficiency, assays of mucosal disaccharidases revealed only inconstant or slight deviations from the control group and were not of diagnostic significance for any of the above-mentioned disorders. Isolated forms of enzyme deficiencies other than lactase deficiency, such as sucrase-isomaltase or trehalase deficiency were not present among 168 investigations carried out from 1972-1982. It is concluded that assay of small intestinal disaccharidase or alkaline phosphatase activities does not expand the diagnostic impact of morphological examination of small bowel biopsy specimens and modern noninvasive methods for the detection of carbohydrate malabsorption. Thus, the method does not appear a necessary or relevant investigation in routine clinical practice.
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PMID:Is the assay of disaccharidase activity in small bowel mucosal biopsy relevant for clinical gastroenterologists? 274 34

The fetal and postnatal activity patterns of different hydrolytic enzymes (alkaline phosphatase, gamma-glutamyltransferase, trehalase, maltase, glucoamylase, lactase, and sucrase) have been examined in mouse renal homogenates. Alkaline phosphatase and gamma-glutamyltransferase activities presented approximately similar changes. They increased from 18 days of gestation up to 30 days after birth. These activities showed marked increases during the 3rd and 4th postnatal weeks. A similar important rise was observed for trehalase activity at the end of the suckling period. Maltase activity increased gradually after birth. Traces of lactase, sucrase, and glucoamylase activities were detected at each developmental stage.
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PMID:[Activity of renal hydrolases in pre- and postnatal development of mice]. 286 26

Kt values for various monosaccharides were determined from sugar-induced increments of the transmural potentials in isolated small intestines of the goldfish, bullfrog, turtle, quail, guinea pig, rat and rabbit, and specificity patterns of the Na+/sugar cotransporters were compared among these animal species. Absolute requirement of the D-pyranose ring structure was seen in all animals. Requirements of C2-OH and C6 were strong, but not absolute, and OH groups on C3, C4, C6 and the O-atom of the pyranose ring were also suggested to participate, in some degree, in the interaction with the carrier. Comparison of the disaccharide-evoked potentials revealed that there were considerable species differences in activities of trehalase, sucrase and lactase among animals examined, but the differences were relatively small for maltase activity.
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PMID:A comparative study of specificity of the intestinal Na+/sugar cotransport among vertebrates. 287 37

Experiments in order to induce food allergy were carried out in guinea pigs. The sensitization with egg albumin, pasteurized cow milk and bovine serum albumin provoked anaphylactic shock. The passive cutaneous anaphylaxis, serum antibodies, liver cytochrome P-450 concentration and the anaphylactic shock were determined. Some correlation between the mortality, anaphylactic antibodies and cytochrome P-450 monooxygenase system was established. The morphology of the jejunal mucosa, the activities of the 5 disaccharidases, the number of immunoglobulin secreting cells (Ig SC) and the mastocytes were investigated in 35 patients with food allergy. Normal mucosa was found in 28 cases as well as a significant decrease of the lactase, sucrase and trehalase activities. An increase of IgM and IgG secreting cells and of mastocytes, different electron microscopic changes in the enterocytes (an increased number of lysosomes, appearance of vesicles in cytoplasma, shortening, enlargement and uneven distribution of microvilli) as well as symptoms of functional activity in the plasmocytes and some others were also revealed. The experimental model obtained is similar to that one in humans according to the enteral way of sensitization the high selectivity of the allergic reaction which is of reagin type as the immunoglobulin changes are involved.
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PMID:Immunological and radioimmunological studies in food allergy. 295 46

The inhibitory action and mechanism of inhibition of two types of alpha-glucosidase inhibitors, acarbose (Bay-g-5421) and 1-deoxynojirimycin derivatives (Bay-m-1099 and Bay-o-1248), on small intestinal carbohydrases (sucrase, isomaltase, glucoamylase, trehalase and lactase) and pancreatic alpha-amylase were compared in vitro using small intestinal brush border membranes and pancreatic homogenates from adult Sprague-Dawley rats. Acarbose at a low (4 microM) concentration strongly inhibited the activities of glucoamylase, alpha-amylase and sucrase (98, 68, and 63%, respectively). At a high (200 microM) concentration, isomaltase activity was also inhibited (28%); effects on trehalase and lactase activities were negligible. Both the 1-deoxynojirimycin derivatives were even more potent inhibitors of sucrase (Ki = 8.6 x 10(-8) M for Bay-m-1099;Ki = 5.0 X 10(-8) M for Bay-o-1248) than acarbose (Ki = 9.9 x 10(-7) M). Whereas glucoamylase activity was strongly inhibited by the 1-deoxynojirimycin derivatives, alpha-amylase activity was not. In contrast to acarbose, the 1-deoxynojirimycin derivatives at high concentrations (20-200 microM) inhibited considerably trehalase and lactase (a beta-galactosidase) activities. The inhibition of lactase activity was stronger by Bay-m-1099 (Ki = 4.9 X 10(-6) M) than by Bay-o-1248 (Ki = 6.7 X 10(-5) M). Where inhibition was seen, kinetic analysis showed fully competitive inhibition of sucrase, isomaltase, trehalase, glucoamylase and lactase by all three inhibitors.
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PMID:Inhibitory mechanism of acarbose and 1-deoxynojirimycin derivatives on carbohydrases in rat small intestine. 296 44

Rat intestinal microvillus membrane contains at least 24 polypeptides, of which 18 can be solubilized using Triton X-114 at 4 degrees C. Upon phase separation at 32 degrees C, 11 proteins separated nearly completely into the detergent-rich phase, while 9 proteins were found exclusively in the aqueous phase. Enzymes which were uniquely included in the detergent phase were alkaline phosphatase, leucine aminopeptidase, gamma-glutamyl transpeptidase, and Ca2+-Mg2+ ATPase. The proteins which were excluded from the detergent phase and found exclusively in the aqueous phase included the disaccharidases (glucoamylase, sucrase-isomaltase, trehalase, lactase) and the ileal receptor for the intrinsic factor-cobalamin complex. Integral membrane proteins can thus be separated during solubilization into two groups prior to further purification or characterization.
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PMID:Phase separation of rat intestinal brush border membrane proteins using Triton X-114. 301 Jul 62

Hydrocortisone administration to infant rats enhanced cellobiase and maltase activities and induced precocious expression of sucrase and trehalase activities along the length of the small intestine. These activity changes reflected proportional concentration increases in the enzymes lactase (EC 3.2.1.23), maltase/glucoamylase (EC 3.2.1.20) and sucrase-isomaltase (EC 3.2.1.48/10). Administration of an equivalent tracer dose of [3H]leucine (by body weight) to control and hydrocortisone-treated infant rats resulted in greater accumulation of label in the carbohydrase pools of the treated rats, suggesting their increased de novo synthesis. The increased concentrations of lactase and maltase/glucoamylase induced by exogenous hydrocortisone were matched by the presence of corresponding greater amounts of label in their brush border pools. Accumulation of label in each of the lactase, maltase/glucoamylase and sucrase-isomaltase pools was generally similar in the hydrocortisone-treated rats, suggesting equivalent stimulation of their synthesis as a group by the humoral agent. The turnover rates of the carbohydrases as a group were found to be similar and did not appear to differ in control and hydrocortisone-treated rats. Total protein synthesis rates were slightly greater in the intestine of the hydrocortisone-treated group of rats.
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PMID:Effects of hydrocortisone on carbohydrase concentrations, de novo synthesis and turnover patterns in immature rat intestine. 308 73

Graft-versus-host reaction (GvHR) was induced in neonatal mice to produce crypt hyperplasia with and without stunted villi. Lactase activity was measured along individual villi of control and GvHR mice using quantitative cytochemistry. Lactase activity increased in control mice as enterocytes migrated over the lower part of the villus. This increase was followed by a period when lactase activity remained approximately constant. Effects produced by GvHR on this normal profile of development included an extension of the distance on the villus over which enterocytes could continue to increase lactase activity, a reduction in the time needed for an enterocyte to express lactase activity at maximal rate, and an overall decrease in the maximal lactase activity expressed by mature enterocytes. These effects have been quantified by fitting logistic curves to the experimental data. Parallel biochemical analyses of intestinal homogenates showed sucrase, isomaltase, trehalase and maltase activities to increase markedly 7-8 days after the injection of parental spleen cells. Attention is drawn to similarities between these results and steroid induced precocious development of intestinal function in neonatal mice.
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PMID:Selective effects of graft-versus-host reaction on disaccharidase expression by mouse jejunal enterocytes. 308 82

Suckling rats were treated every 8 h by intragastric instillation of 16,16-dimethyl prostaglandin E2 (PG) in a dose of 25 micrograms kg-1 (PG25), or 100 micrograms kg-1 (PG100), or saline from postnatal day 7-11. PG increased small intestinal villus length and crypt depth, most markedly in the duodenum, leading to a mucosal height of 543 +/- 24 microns after saline, 670 +/- 26 microns after PG25 and 823 +/- 40 microns after PG100. In the proximal small bowel, PG100 raised the mean activities of sucrase by 439%, maltase by 98%, trehalase by 584%, lactase by 58% and alkaline phosphatase by 76%. In the distal small intestine, only sucrase and trehalase activities were stimulated whereas other enzymes were depressed. PG25 caused similar but less pronounced changes of enzyme activities. Eight hours after both the last PG25 and the last PG100 dose, plasma gastrin and corticosterone levels were decreased while thyroxine remained unchanged. The effect of a single dose of 100 micrograms kg-1 PG or saline was also tested on 5- and 11-day-old rats; they were killed 16 h after PG administration. An increase in villus length occurred along the entire small intestine of rats treated on day 5, and also in the ileum of rats treated on day 11. In the proximal intestine, maltase and trehalase were stimulated after early and late treatment and, in addition, sucrase and lactase after late treatment. Serum corticosterone levels were found to be significantly higher 2-6 h after PG100 than in the controls and then decreased gradually.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of 16,16-dimethyl prostaglandin E2 on small intestinal mucosa in suckling rats. 311 65


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