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

Fasting reduced small intestinal length. It also decreased mucosal weight, DNA and protein content, and concentrations of enterokinase, maltase, and sucrase in both duodenal and jejunal segments. In contrast, the concentrations of lactase and leucine aminopeptidase were not affected. Concomitantly, serum insulin levels dropped to one-fifth of the control levels while serum glucose concentrations showed a lesser degree of reduction. Glucose supplementation alone raised the serum insulin level, prevented the decrease in DNA content, and showed a protective effect on mucosal protein, mucosal weight, mucosal thickness, and villus height. Glucose also protected the sucrase and maltase concentrations; more significantly for maltase in the jejunal segment. Insulin alone, although it increased the serum insulin level to that found with glucose supplementation alone, had no protective effect on the loss in protein, DNA, and most enzymes except for maltase concentration in the jejunal segment. Addition of insulin to glucose did not modify the glucose effect on the contents of DNA, protein, and concentrations of sucrase and maltase. These results suggest that the glucose effect on the mucosa is not mediated by insulin. In addition, the retention of both maltase and sucrase activities through only glucose supplementation suggests the loss of maltase and sucrase in fasting is due to nutrient rather than specific substrate restriction.
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PMID:Effect of glucose and insulin on small intestinal brush border enzymes in fasted rats. 640 48

The study of deficiencies of small intestinal brush-border hydrolases increased our knowledge about the specific functions of hydrolases in the digestion of smaller molecules on the microvillus surface of the absorptive cells. The sucrase-isomaltase (SI) complex has been shown to be synthesized as a precursor (pro-sucrase-isomaltase) which is then incorporated into the membrane. The hydrophobic N-terminal end of the molecule is anchored in the lipid bilayer. In SI deficiency the molecular base of the disease is still not clear. Absence of SI activity could be due to complete lack of precursor synthesis or to structural changes within the N-terminal end of the SI-complex. Deficiencies of peptide hydrolases have not been reported with the exception of enteropeptidase (EP). Here a congenital deficiency of the enzyme was observed as the primary defect in enzyme synthesis within the enterocytes and as a secondary defect due to exocrine pancreatic insufficiency. In contrast to the primary EP deficiency, the activity of EP can be restored in the cases of exocrine pancreatic insufficiency by treatment with pancreatic extracts. Primary lactase deficiency exists in various forms. Besides congenital lactase deficiency, the late onset or adult type of lactase deficiency has been observed. The latter occurs in many different ethnic groups around the world. Here, using gel electrophoresis and immunoelectrophoresis, the lack of enzyme activity could be shown to be a primary defect in enzyme protein synthesis. In man and in the rat, two different lactases have been identified. In contrast to adult lactase, fetal lactase contains sialic acid at the end of carbohydrate side chains.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Clinical significance of enzymatic deficiencies in the gastrointestinal tract with particular reference to lactase deficiency. 643 79

The activities of maltase, lactase, alkaline phosphatase and enterokinase were followed in the small intestine of rats during prenatal development. These enzymes were detectable only after the 17th day of gestation. Furthermore, each enzyme exhibited a different pattern of prenatal presence. Maltase activity appeared first (day 18), followed by lactase and alkaline phosphatase (day 19) and then enterokinase (day 20). Except for enterokinase, all of the enzymes attained a level of activity close to the newborn levels at the final day of gestation. Induced intrauterine growth retardation during the 3rd trimester led to a decrease in intestinal weight proportional to the reduction of body weight. These decrease in size of the small intestine was caused by a reduction in cell number rather than cell size. Induced intrauterine growth retardation also resulted in a selective reduction in the specific activities of lactase and alkaline phosphatase, but not of enterokinase and maltase. These results suggest that reduction in maternofetal blood flow in the 3rd trimester of gestation will cause a selective decrease in some brush border enzymes (lactase and alkaline phosphatase) but does not effect others (maltase and enterokinase).
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PMID:Effect of intrauterine growth retardation on the activities of fetal intestinal enzymes in rats. 678 32


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