Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chemical galactosylation of human liver tissue lysosomal alpha-glucosidase was carried out. As a result of the modification some physicochemical properties of the enzyme were altered, while its stability and catalytic activity were maintained. An ability of the galactosylated alpha-glucosidase to interact with asialoglycoprotein receptor from mice liver tissue was studied in vitro. The reaction required Ca2+. A specific inhibitor of the receptor, N-acetyl galactosamine, as well as high concentrations of native glycoproteins and neoglycoproteins containing terminal galactose inhibited the receptor binding of the 125I-galactosylated alpha-glucosidase. Native alpha-glucosidase was not bound with the receptor. Antireceptor antibodies inhibited similarly binding of both native ligand, asialoorosomucoid and the galactosylated alpha-glucosidase. These data on specific interaction between the galactosylated form of alpha-glucosidase and asialoglycoprotein receptor are discussed in connection with the problem of directed transport of the enzyme into liver parenchymatous cells by means of receptor-dependent endocytosis, which may be of importance in development of enzymotherapy of hereditary lysosomal enzymopathies.
 ...
PMID:[Chemical galactosylation of acid alpha-glucosidase to provide directed transport of the enzyme into lysosomes of liver parenchymal cells]. 282 27

Previous studies have shown that chronic administration of D-galactosamine (GalNH2) in rats produces alpha 1-antiprotease (AAP) deficiency and causes accumulation of aberrantly glycosylated AAP in hepatic granules. In order to examine the disordered mechanism which produces this altered glycosylation, the activities of 6 glycosidases in liver homogenates of control and AAP-deficient rats were determined. GalNH2 treatment increases acid pH glycosidase activity, while it decreases intermediate pH alpha-mannosidase and alpha-glucosidase activities. beta-D-Glucosidase, beta-D-mannosidase and beta-D-N-acetylglucosaminidase activities, measured at acid pH, increase more than 2-fold in the GalNH2-treated rats compared to controls. alpha-D-Glucosidase activity measured at intermediate pH decreases 2.5-fold in the experimental rats. alpha-L-Fucosidase and acid phosphatase activities are not significantly changed by GalNH2 treatment. alpha-D-Mannosidase activity can be separated into 2 fractions by ion exchange chromatography. Acid pH alpha-D-mannosidase is increased nearly 2-fold in the GalNH2-treated rats. Intermediate pH alpha-D-mannosidase optimum is decreased alpha-D-mannosidase activities have been observed in humans with AAP deficiency. alpha-Glucosidases and alpha-mannosidases play a crucial role in glycoprotein synthesis. The altered synthesis and structure of AAP in GalNH2-induced AAP deficiency may be a reflection of altered enzyme activities.
 ...
PMID:Altered glycosidase activity in the liver of rats with galactosamine-induced alpha 1-antiprotease deficiency. 383 42

The activities of lactase, sucrase, maltase and gamma-glutamyl transferase (gamma-GT) were determined in homogenates of rat jejunal mucosa 24 h after acute administrations of D-galactosamine (GALN) (1.855 mmol/kg; i.p. injection) and alpha-naphthyl-isocyanate (ANIT) (0.540 mmol/kg; given by gastric tube). The animals were fasted either 24 h or 72 h prior to sacrifice. In rats fasted only 24 h, GALN treatment resulted in a pronounced decrease in lactase and in a moderate elevation of sucrase and maltase. ANIT clearly reduced lactase and, to a lesser extent, sucrase, while it increased maltase. Seventy-two hour fasting has a modifying role. All disaccharidase activities tended to decrease, except for maltase in the ANIT treated group, where an increase was recorded. gamma-GT showed no significant changes after either GALN or ANIT treatment in rats fasted 24 h. However, the 72-hour food deprivation diminished it in ANIT intoxication. It is obvious that the intestinal enzymes are influenced by the hepatic damage produced by GALN and ANIT.
 ...
PMID:Influence of D-galactosamine and alpha-naphthylisothiocyanate on the activities of some intestinal enzymes. 615 Aug 89

Galactosamine does not support growth of Bacteroides thetaiotaomicron. Despite this, galactosamine was more effective than utilizable carbohydrates such as glucose in preventing synthesis of the inducible enzymes alpha-glucosidase and chondroitin lyase. Galactosamine also stopped overall protein synthesis. By contrast glucose and other utilizable carbohydrates increased the rate of protein synthesis. Addition of glucose to bacteria which had been treated with galactosamine restored the ability of the bacteria to synthesize protein and to produce inducible enzymes. Moreover, when B. thetaiotaomicron was incubated with [1-14C]galactosamine for 30 min at 37 degrees C, about one-third of the label which was taken up by the cells comigrated with glucosamine-6-phosphate on a thin-layer chromatogram. Thus galactosamine appears to be phosphorylated by the bacteria. After 2 h incubation of the bacteria with [1-14C]galactosamine, there was a significant increase in the amount of label which could be extracted from acidified extracellular fluid with diethyl ether. This indicates that galactosamine can be metabolized to the level of volatile fatty acids. The rate of uptake of galactosamine and the amount of labeled fatty acids produced from galactosamine were both much lower than the values obtained when glucosamine was the substrate. Thus, although some metabolism of galactosamine occurs, the rate is apparently too slow to enable galactosamine to support growth of B. thetaiotaomicron.
 ...
PMID:Galactosamine inhibition of protein synthesis in Bacteroides thetaiotaomicron. 636 11

Fertilization in Bufo arenarum requires the sperm to penetrate the egg envelopes. The incubation of isolated vitelline envelopes with sperm induces the acrosome reaction, releasing proteases and glycosidases to the media. In the present work N-acetyl-beta-D-glucosaminidase, beta-D-galactosidase, beta-D-glucosidase, alpha-D-mannosidase, alpha-L-fucosidase, and alpha-D-glucosidase activities are measured in spermatozoa. N-acetyl-beta-D-glucosaminidase is the major sperm glycosidase activity assayed. However, N-acetyl-beta-D-galactosamine show competitive inhibitory effect. The glycosidase pH optimum is 3.5 being inhibited at pHs higher than 7.5. In our study, N-acetyl-beta-D-glucosaminidase is the only glycosidase that in vitro binds to vitelline envelopes in conditions that resemble natural fertilization media. The isolation of the active enzyme will allow studies of its role in fertilization. The enzyme has been purified in a two-step procedure. After native gel electrophoresis, the activity-stained band was cut out and the eluted enzyme was finally subjected to ConA-sepharose chromatography. In SDS-PAGE, the denatured enzyme migrates as a single band with a molecular mass of 45 kDa. Furthermore, analysis by size-exclusion on HPLC showed a peak of activity at around 45 kDa. Preliminary localization studies showed higher relative activity in the acrosomal content. In addition, 10% of the N-acetyl-beta-D-glucosaminidase activity was associated with the reacted sperm. By in vitro fertilization assay, it was observed that the inhibition of the enzyme results in the inhibition of fertilization. This last study shows that N-acetyl-beta-D-glucosaminidase plays an important role in toad fertilization.
 ...
PMID:Purification and biological characterization of N-acetyl beta-D glucosaminidase from Bufo arenarum spermatozoa. 1098 20