Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Radiolabeled cholesteryl oleate, when incorporated into phospholipid vesicles, was hydrolyzed at acid pH by an enzyme present in rabbit aortic homogenates. In contrast, cholesteryl oleate presented as an acetone dispersion was not effectively hydrolyzed at acid pH under identical conditions. Using the vesicle preparation as substrate, a sensitive assay system for the acid hydrolase was developed in which hydrolysis was proportional to protein concentration and incubation time, and was independent of substrate concentration. The physical state of the vesicles was apparently not altered by the assay conditions, and no hydrolysis of the vesicle-associated phospholipid was detected. Acid cholesterol esterase activity in atherosclerotic aortic tissue was 2.5-fold greater than that of control tissue, and even greater increases were observed in the activities of other lysosomal enzymes (N-acetyl-beta-d-glucosaminidase and beta-glucuronidase). Glucose-6-phosphatase activity was also increased in aortas from cholesterol-fed animals while 5' nucleotidase activity remained unchanged. Labeled triolein also was incorporated into phospholipid vesicles and was hydrolyzed by an acid lipase in aortic tissue. Similarities between triolein and cholesteryl oleate hydrolysis existed with respect to pH optimum and the effect of cholesterol feeding on activity, suggesting that a single enzyme may hydrolyze both lipids.
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PMID:Effect of atherosclerosis on lysosomal cholesterol esterase activity in rabbit aorta. 1 38

An acid cholesteryl ester hydrolase activity associated with a fraction containing mitochondria and lysosomes from rat lactating mammary glands was found to have a pH optimum of 5.0. Its sedimentation pattern was closely related to that of the lysosomal enzyme markers acid phosphatase and beta-glucuronidase, suggesting that the activity is associated with the lysosomes. The enzyme was strongly inhibited by Cu2+, but was inhibited little by other divalent metal ions. Acid cholesteryl ester hydrolase activity was almost completely abolished by p-hydroxy-mercuribenzoate, but this effect was reversed in the presence of an equimolar concentration of reduced glutathione (GSH), indicating that the enzyme requires free sulfhydryl groups for activity. These properties are similar to those of acid, lysosomal cholesteryl ester hydrolases found in other tissues. Acid cholesteryl ester hydrolase activity was 8-14 fold higher in mammary tissue from lactating as compared to virgin rats. Neutral cholesteryl ester hydrolase activities associated with the microsomal and cytosolic subcellular fractions were also increased in lactating glands, but to a lesser extent. In addition, a 2-fold increase in the activities of both the acid and microsomal neutral enzymes was seen during the first few days of lactation, while the cytosolic neutral activity remained constant. These results suggest that mammary gland cholesteryl ester hydrolases have a role in the regulation of cholesterol metabolism in mammary cells, and in the provision of cholesterol for secretion into milk.
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PMID:Cholesterol metabolism in the rat lactating mammary gland: the role of cholesteryl ester hydrolase. 180 94

The inhibitory effect of a protein isolated from rat serum on lysosomal acid cholesteryl ester hydrolase (acid CEH; EC.3.1.1.13) activity was studied. An inhibitor was purified from rat serum following ultracentrifugation and heat treatment using column chromatography on Sephacryl S-200 and ultrafiltration. The purified inhibitor appeared as a single protein band in sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The molecular weight of the inhibitor was 28,000 Daltons as judged by gel filtration on Sephacryl S-200 and SDS-polyacrylamide gel electrophoresis. The purified inhibitor was shown to be apolipoprotein A-I (apo A-I), the major apolipoprotein of high-density lipoprotein (HDL), using immunoprecipitation with rat anti-apo A-I immunoglobulin (Ig)G. Inhibition of acid CEH activity by apo A-I was dependent on the concentration of apo A-I. The values of Vmax obtained were similar with or without apo A-I. Apo A-I of various other mammalian species, including human, bovine and rabbit, also inhibited acid CEH activity. Other apolipoproteins, such as apo A-II and apo B, also showed inhibiting activity. On the other hand, apo A-I had no effect on the activity of other enzymes found in lysosomes, such as cathepsin D, beta-glucuronidase and acid phosphatase. The results suggest that apolipoproteins may play a role in the regulation of hydrolysis of cholesteryl esters in lipoproteins, that have been transferred to the liver, and that the inhibition of acid CEH activity by apo A-I may be a characteristic of the lipid-binding protein or be due to changes of the lipid/water interface.
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PMID:Properties of an acid cholesteryl ester hydrolase inhibitor from rat serum. 212 53

Normal arterial foci which take up Evans blue dye (EBD) in vivo are believed to represent atherosclerosis-prone, hemodynamically stressed foci compared to areas which exclude dye. We have used the rabbit EBD model to examine focal aortic hydrolases of blue areas versus white areas, and we report herein significant focal variations of hydrolase activities. Enzymes measured included neutral alpha-glucosidase, N-acetyl-beta-glucosaminidase, alpha-mannosidase, acid alpha-glucosidase, beta-galactosidase, beta-glucuronidase, cathepsin C, and acid cholesteryl esterase (ACE); specific activities were expressed on the basis of tissue DNA. In correlative areas of EBD uptake in normal rabbit aortic arch, ACE activity averaged 17% higher and cathepsin C activity averaged 37% lower than activities of areas free of EBD in the descending thoracic aorta (P less than 0.02). None of the glycosidases studied differed significantly between blue and white aortic areas. These findings indicate that discrete, intrinsic differences of hydrolytic enzyme activities exist in the normal rabbit aorta in areas delineated by in vivo EBD uptake, areas recognized as lesion-prone vs lesion-resistant.
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PMID:Intrinsic focal variations of rabbit aortic hydrolase activities. 276 19

Cupric ions were administered subcutaneously to male Sprague-Dawley r rats at a single dose of 200 mumol/kg. At 24 hr after administration, a remarkable increase of total and free cholesterol was seen in the rat serum. Also, when lecithin-cholesterol acyltransferase (LCAT) (E.C. 2.3.1.43) activity was expressed as the percentage of the total serum that free cholesterol esterified, the acyltransferase activity in rats treated with cupric ions showed a slight decrease while the triglyceride content in rat serum and liver decreased by 54% and 61%, respectively. However, the content of hepatic cholesterol in rats treated with cupric ions did not show such a marked change. On the other hand, acid cholesteryl ester hydrolase activity (Acid CEH) (E.C. 3.1.1.14) in liver lysosomes of rats treated with cupric ions showed a marked decrease with increasing cupric ion concentration both in vivo and in vitro. Furthermore, cupric ions caused a marked release of the lysosomal enzymes cathepsin D and beta-glucuronidase into the cytosolic fraction. The changes in acid cholesteryl ester hydrolase activity induced by cupric ions appear to be a direct effect of cupric ions on the enzyme. These results suggest that excessive cupric ion concentrations could cause various disorders in lipid metabolism.
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PMID:Effect of cupric ions on serum and liver cholesterol metabolism. 345 Oct 6

The activity of lysosomal acid cholesteryl ester hydrolase (acid CEH, EC 3.1.1.13) in rat liver was determined at 3, 5, 7, 10 and 20 wk following birth. The levels of acid CEH activity showed a marked decrease as rats grew older, whereas those of other lysosomal marker enzymes, such as acid phosphatase, beta-glucuronidase and cathepsin B and D, showed only a slight decrease. On the other hand, acid CEH activity was detected in all subcellular fractions obtained from rat liver, but the enzyme activity in these fractions did not show the age-related decrease observed in the lysosomal fraction. The results presented here suggest that the marked alteration of lysosomal acid CEH activity that accompanies aging may be related to its possible involvement in the regulation of cholesterol concentration in rat liver.
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PMID:The activity and properties of a hepatic acid cholesteryl ester hydrolase obtained from rats of different age groups. 366 30

An inhibitor of lysosomal acid cholesteryl ester hydrolase (Acid CEH), (EC 3.1.1.13) was found in the cytosolic fraction of rat liver and various other tissues. The extent of the inhibitory effect was dependent on the concentration of the cytosolic protein. The Acid CEH inhibitor was heat-labile, non-dialyzable, and its inhibitory activity significantly decreased by trypsin or chymotrypsin digestion, but not by lipase digestion. The inhibitor had no effect on the activity of cathepsin D, beta-glucuronidase and acid phosphatase, which are other enzymes found in lysosomes. The present findings suggest that the inhibitor may be involved in the regulation of the hydrolysis of cholesteryl esters in lipoproteins that have been transferred into the liver.
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PMID:Characterization of a cytosolic protein inhibiting lysosomal acid cholesteryl ester hydrolase. 650 18