Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Variations in the dietary fatty acid composition and cholesterol content are associated with alterations in the intestinal uptake of hexoses and lipids in control and diabetic rats. Changes in the composition of the brush membrane (BBM) lipids may provide a possible mechanism for the observed alterations in transport properties. Accordingly, control and streptozotocin diabetic animals were fed one of four isocaloric semisynthetic diets for two weeks: beef tallow with low cholesterol, beef tallow with high cholesterol, fish oil with low cholesterol or fish oil with high cholesterol. BBM were prepared and assessed for marker enzyme activity and lipid composition. Fish oil feeding was associated with a reduction in total phospholipid content in control and diabetic jejunal and ileal BBM; this fall in total phospholipids was due to a reduction in BBM sphingomyelin. Cholesterol supplementation increased control jejunal BBM sucrase activity in animals fed beef tallow but reduced sucrase activity in animals fed fish oil. In fish oil fed diabetic animals, jejunal and ileal BBM alkaline phosphatase activity was increased with cholesterol supplementation. The elevation in BBM total phospholipids (phosphatidylethanolamine) associated with diabetes in beef tallow fed animals was not observed in the jejunal BBM of animals fed fish oil or in the ileal BBM of animals fed fish oil with high cholesterol. Thus, (a) feeding an omega-3 polyunsaturated fatty acid diet (fish oil) reduced total phospholipid content in BBM of control and diabetic animals, primarily due to a reduction in sphingomyelin; and (b) feeding an omega-3 polyunsaturated fatty acid diet or dietary cholesterol supplementation alter the activity of BBM enzymes. These results suggest that variations in dietary fat composition and the associated changes in BBM composition and enzyme activity contribute to altered intestinal function in diabetes.
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PMID:Isocaloric modification of dietary lipids influences intestinal brush border membrane composition in diabetic rats. 180 79

Experiments were conducted, using a nonspecific lipid transfer protein, to vary the cholesterol/phospholipid molar ratio of rat proximal small intestinal microvillus membranes in order to assess the possible role of cholesterol in modulating enzymatic activities of this plasma membrane. Cholesterol/phospholipid molar ratios from 0.71 to 1.30 were produced from a normal value of 1.05 by incubation with the transfer protein and an excess of either phosphatidylcholine or cholesterol/phosphatidylcholine liposomes for 60 min at 37 degrees C. Cholesterol loading or depletion of the membranes was accompanied by a decrease or increase, respectively, in their lipid fluidity, as assessed by steady-state fluorescence polarization techniques using the lipid-soluble fluorophore 1,6-diphenyl-1,3,5-hexatriene. Increasing the cholesterol/phospholipid molar ratio also decreased alkaline phosphatase specific activity by approximately 20-30%, whereas decreasing this ratio increased this enzymatic activity by 20-30%. Sucrase, maltase, and lactase specific activities were not affected in these same preparations. Since the changes in alkaline phosphatase activity could be secondary to alterations in fluidity, cholesterol, or both, additional experiments were performed using benzyl alcohol, a known fluidizer. Benzyl alcohol (25 mM) restored the fluidity of cholesterol-enriched preparations to control levels, did not change the cholesterol/phospholipid molar ratio, and failed to alter alkaline phosphatase activity. These findings, therefore, indicate that alterations in the cholesterol content and cholesterol/phospholipid molar ratio of microvillus membranes can modulate alkaline phosphatase but not sucrase, maltase, or lactase activities. Moreover, membrane fluidity does not appear to be an important physiological regulator of these enzymatic activities.
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PMID:Cholesterol modulates alkaline phosphatase activity of rat intestinal microvillus membranes. 337 34