Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.20 (alpha-glucosidase)
4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glycoprotein processing inhibitors prevent the normal processing of N-linked glycoproteins by inhibiting specific glycosidases involved in these reactions. Thus, a number of compounds are now known that inhibit alpha-glucosidase I and alpha-glucosidase II and therefore prevent the removal of glucoses from the high-mannose chains. Some of these compounds are more potent inhibitors of one or the other of these glucosidases. There are also a number of inhibitors that affect one of the processing alpha-mannosidases (i.e. mannosidase I or mannosidase II). These compounds; especially the glucosidase inhibitors, have been valuable tools to help us understand the role of carbohydrate in viral envelope glycoprotein function. Such processing inhibitors have also been used with various tumorigenic cell lines to determine the function of N-linked glycoproteins in cancer.
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PMID:Glycosidase inhibitors as antiviral and/or antitumor agents. 181 22

Isolates from a collection of phenotypically melibiose-negative (Mel-) Streptococcus mutans from widely-scattered geographical locations were examined and found to lack the activities of the enzymes alpha-galactosidase and alpha-glucosidase, in addition to being unable to transport melibiose. Cloned fragments of S. mutans DNA from the region of the chromosome carrying the genes for alpha-galactosidase (aga), sucrose phosphorylase (gtfA), and dextran glucosidase (dexB), as well as the genes encoding components of the binding-protein-dependent uptake system for raffinose and melibiose, were used in hybridization studies for investigation of the genetic basis of the Mel-phenotype. A region of at least 12 kilobases, containing all the above genes, was found to be deleted from the chromosome of the Mel- strains. It appears that this region of the chromosome is not essential for survival of S. mutants in the oral cavity. The reason for the frequent occurrence of deletions, as opposed to other forms of mutational events, is unknown.
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PMID:Chromosomal deletions in melibiose-negative isolates of Streptococcus mutans. 183 26

The purpose of the present study was to establish the effect of the carcinogen 1,2 dimethylhydrazine on the activities of the jejunal glucosidases and to assess the possible modifying effect of different diets. Two control groups of Wistar albino rats were used - fed standard pellet diet and fed the same diet + 1,2 dimethylhydrazine treatment. Six experimental groups treated with 1,2 dimethylhydrazine were provided. One of them was fed standard diet, containing 30% of wheaten bran and the other 5 groups received high-lipid diets, containing 30% of different fats. The rats were injected subcutaneously once a week for 12 weeks with 20 mg 1,2 dimethylhydrazine/kg b.m. and left for 12 weeks in order to develop a tumor growth. The activities of 5 glucosidases (lactase, maltase, sucrase, palatinase and cellobiase) were determined in homogenates from jejunal mucosa taken near by the tumors and in homogenates from the tumors themselves. An expressed decrease of the jejunal glucosidase activities near the tumors and in the tumors was established. The animals fed 30% wheaten bran diet did not develop tumorigenesis and showed comparatively slight decrease of the enzyme activities. In general, the high-fat regimens did not exert such a preventive effect.
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PMID:Changes in the activities of jejunal glucosidases in experimental intestinal tumorigenesis induced by 1,2 dimethylhydrazine in rats fed different diets. 191 61

The seminal marker of epididymal function alpha-1, 4-glucosidase was localized histochemically in the cytoplasm of the efferent duct epithelium and the brush border of the entire length of the human epididymis. Quantification using the specific inhibitor castanospermine revealed strongest activity in the corpus and cauda regions. Selective inhibition of the brush border enzyme activities by maltotriose identified these as the neutral isoenzymes. Despite detection of alpha-glucosidase in the renal tubules of all the animals studied, the enzyme was not detectable in epididymides of hamsters or mice. In rabbits and monkeys, it was absent from the entire brush border but present weakly in the cytoplasm of the proximal epididymides. An enzyme distribution pattern similar to that in the human epididymis was found in rats, except for the absence of histochemical staining at pH 6.5 from the initial segment and distal cauda epididymidis. Experiments in which endogenous testosterone was depleted in rats demonstrated the dependence of epididymal alpha-glucosidase on androgen, albeit with a low sensitivity. This study suggests the rat to be a suitable model for the investigation of the role of epididymal alpha-glucosidase in fertility.
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PMID:Histochemical localization and quantification of alpha-glucosidase in the epididymis of men and laboratory animals. 211 30

The gene coding for Bacillus cereus ATCC7064 (mesophile) oligo-1,6-glucosidase was cloned within a 2.8-kb SalI-EcoRI fragment of DNA, using the plasmid pUC19 as a vector and Escherichia coli C600 as a host. E. coli C600 bearing the hybrid plasmid pBCE4 accumulated oligo-1,6-glucosidase in the cytoplasm. The cloned enzyme coincided absolutely with B. cereus oligo-1,6-glucosidase in its Mr (65,000), in its electrophoretic behavior on a polyacrylamide gel with or without sodium dodecyl sulfate, in its isoelectric point (4.5), in the temperature dependence of its stability and activity, and in its antigenic determinants. The nucleotide sequence of B. cereus oligo-1,6-glucosidase gene and its flanking regions was determined with both complementary strands of DNA (each 2838 nucleotides). The gene consisted of an open reading frame of 1674 bp commencing with a ATG start codon and followed by a TAA stop codon. The amino acid sequence deduced from the nucleotide sequence predicted a protein of 558 amino acid residues with a Mr of 66,010. The amino acid composition and Mr were comparable with those of B. cereus oligo-1,6-glucosidase. The predicted N-terminal sequence of 10 amino acid residues agreed completely with that of the cloned ligo-1,6-glucosidase. The deduced amino acid sequence of B. cereus oligo-1,6-glucosidase was 72% and 42% similar to those from Bacillus thermoglucosidasius KP1006 (DSM2542, obligate thermophile) oligo-1,6-glucosidase and from Saccharomyces carlsbergensis CB11 alpha-glucosidase, respectively. Predictions of protein secondary structures along with amino acid sequence alignments demonstrated that B. cereus oligo-1,6-glucosidase may take the similar (alpha/beta)8-barrel super-secondary structure, a barrel of eight parallel beta-strands surrounded by eight alpha-helices, in its N-terminal active site domain as S. carlsbergensis alpha-glucosidase and Aspergillus oryzae alpha-amylase.
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PMID:Primary structure of the oligo-1,6-glucosidase of Bacillus cereus ATCC7064 deduced from the nucleotide sequence of the cloned gene. 212 57

The literature pertaining to epididymal proteins and their functions in fertilization is reviewed. Animal studies have indicated that specific epididymal proteins may be involved in aspects of sperm motility, sperm-zona binding and the acrosome reaction. If analogous proteins in the human exist, use could be made of them in the andrology clinic. Currently, only one specific epididymal protein (alpha-glucosidase) is routinely measured for semen analysis. Glucosidase secretion, in addition to reflecting inflammation of the organ, is used in conjunction with other markers of human fertility to identify patients with ductal occlusion for whom bypass operations may be useful therapy. Glucosidase inhibitors have been used to improve the assay, by establishing true semen blank values, and to quantify histochemical activity in frozen tissue sections. From its localization in the human corpus and cauda epididymidis, neutral glucosidase can not be used to identify occlusion in the proximal regions of the duct. Other proteins may be valuable markers of these regions. In the future, other specific proteins of epididymal origin found in seminal fluid could well illuminate dysfunction of the organ in cases of infertility or be end-points of the disruptive action of drugs aimed at the epididymis.
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PMID:Secretory proteins from the epididymis and their clinical relevance. 213 67

Seminal alpha-glucosidase has been used clinically as a marker of epididymal function. In this study enzyme inhibitors were used to increase the specificity of the human seminal alpha-glucosidase assay and improve its diagnostic value as an indicator of distal epididymal occlusion in cases of azoospermia. Sodium dodecylsulphate was added to the sample to eliminate the interfering acid isoenzyme secreted by the prostate gland, and castanospermine was used with semen pools to provide a semen blank for the assay by eliminating non-glucosidase-regulated degradation of the substrate. With both inhibitors included in the assay, glucosidase activity in semen samples from 17 fathers was measured to provide reference values for the clinic (lower threshold 18 mU per ejaculate). With the improved assay glucosidase was non-detectable in 8 out of 11 cases of proven and 5 out of 8 cases of suspected ductal obstruction; other azoospermic patients with distal occlusion had values below 11 mU per ejaculate.
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PMID:Improvement in the assessment of human epididymal function by the use of inhibitors in the assay of alpha-glucosidase in seminal plasma. 220 50

An isomaltose-hydrolyzing alpha-D-glucosidase from the alkalophilic Bacillus designated strain F5 was purified to an electrophoretically homogeneous state. The molecular weight of the purified glucosidase was 60,000 by SDS-poly(acrylamide) gel electrophoresis, and 63,000 by Sephacryl S-200 gel-filtration chromatography. The enzyme was most active for isomaltose at pH 6.0-6.5 and 45 degrees, and stable up to 50 degrees at pH 7.0 and in the range of pH 6.0-9.0 at 50 degrees by 10-min incubation. The apparent Vmax and Km values for isomaltose were 34.5 mumol.min-1.mg-1 of protein, and 3.33 mM. Panose and isomaltotriose are the best substrates for this enzyme. The restricted substrate specificity indicated the assignment of the enzyme to be an oligo-1,6-glucosidase (dextrin 6-alpha-glucanohydrolase; EC 3.2.1.10), but it was suggested that it could be a new type of oligo-1,6-glucosidase on the basis of its action on a series of (1----4)-alpha-malto-oligosaccharides.
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PMID:Purification and properties of an oligo-1,6-D-glucosidase from an alkalophilic Bacillus species. 234 49

Predictions of protein secondary structure are used with amino acid sequence alignments to show that the N-terminal domains of cyclodextrin glucanotransferases and a yeast alpha-glucosidase may have the same super-secondary structure as alpha-amylases, i.e. an (alpha/beta)8-barrel fold. Sequence similarities provide evidence that glucanotransferases, and possibly the glucosidase, are, like alpha-amylases, Ca2+-containing enzymes. The relationship between substrate specificity and the nature of the amino acid residues proposed at the active site is discussed for the transferases and alpha-glucosidase. A set of three programs for an Apple IIe computer to carry out the calculations described by Garnier, Osguthorpe & Robson [(1978) J. Mol. Biol. 120, 97-120] and a set of four programs for an Apple IIe computer to carry out the calculations described by Levin, Robson & Garnier [(1986) FEBS Lett. 205, 303-308] have been deposited as Supplementary Publication SUP 50149 (25 pages) at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1989) 257, 5.
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PMID:A super-secondary structure predicted to be common to several alpha-1,4-D-glucan-cleaving enzymes. 252 86

A new mechanism-based glucosidase inactivator, conduritol aziridine (1,2-dideoxy-1,2-epimino-myo-inositol), has been synthesised from myo-inositol. This aziridine inactivates both the beta-glucosidase from Alcaligenes faecalis and the alpha-glucosidase from yeast according to the expected pseudo-first order kinetics. Inactivation constants measured are Ki = 3.0mM, ki = 0.077 min-1 for the beta-glucosidase, and Ki = 9.5mM, ki = 0.39 min-1 for the alpha-glucosidase. Evidence for irreversible inactivation is provided by the lack of reactivation upon dilution of inactivated enzyme into buffer containing substrate.
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PMID:Conduritol aziridine: a new mechanism-based glucosidase inactivator. 267 41


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