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)

When cells of Propionibacterium freudenreichii were incubated under fasting conditions and then plated in the presence of an inhibitor of protein synthesis, a variable but significant (greater than 10(-2) fraction of the population changed their morphology from rod to sphere, with a considerable thickening of the cell wall. This change was accompanied by metabolic and antibiotic-resistance modifications, including the synthesis of at least one new enzyme (alpha-glucosidase), and by the simultaneous appearance of several new species of DNA, presumably plasmids. The round cells grew faster than the parent strain and maintained their morphology indefinitely when propagated on complex medium containing glucose as the main carbon source. However, when glucose was omitted, cells returned to the rod form and regained their previous characteristics, including the absence of detectable plasmids.
J Gen Microbiol 1988 Feb
PMID:Induction of a stable morphological change in Propionibacterium freudenreichii. 304 32

A rapid and improved method to obtain purified lactase from rat intestine is described. The purification procedure involved only two chromatographic steps. The degree of purification was far above (500 fold) the values reached with classical methods. Rabbit antisera raised to the purified lactase were characterized using conventional immunological techniques. The specificity of the lactase antibodies was confirmed by the lack of interference on maltase, aminopeptidase and alkaline phosphatase activities measured after papain extraction of the membrane proteins.
Gen Physiol Biophys 1986 Feb
PMID:Improved purification of rat intestinal lactase. 309 77

The effects of glucocorticoids (hydrocortisone, dexamethasone) and insulin on enzymatic activities of the intestinal brush border membrane were investigated in an anuran amphibian, Alytes obstetricians, before and during experimental metamorphosis produced by immersion into a thyroxine solution. During experimental metamorphosis, a new epithelium (secondary epithelium) replaces the degenerating primary epithelium. The enzymes studied were three glucidases (maltase, glucoamylase, trehalase) and alkaline phosphatase. In tadpoles reaching the end of premetamorphosis, hormones were injected every day (hydrocortisone, dexamethasone: 25 micrograms/g body wt/day; insulin: 5 mU/g body wt/day, for 3 and occasionally 6 consecutive days. Under such conditions, most of the activities in the primary epithelium increased or remained stable. In animals which completed experimental metamorphosis, the secondary epithelium formed. Hydrocortisone (25 micrograms/g body wt/day) and insulin (5 mU/g body wt/day) treatments significantly decreased the enzymatic activities of the new brush border membrane in animals which received one hydrocortisone and/or insulin injection per day, during 3 consecutive days. Such results, which previously had not been obtained systematically in spontaneously metamorphosing tadpoles (El Maraghi-Ater, Mesnard, and Hourdry (1986). Gen. Comp. Endocrinol. 61, 53-63), emphasize the relative independence of the intestinal metabolism during experimental and spontaneous metamorphosis.
Gen Comp Endocrinol 1987 Mar
PMID:Hormonal control of the intestinal brush border enzyme activities in developing anuran amphibians. II. Effects of glucocorticoids and insulin during experimental metamorphosis. 310 33

Culture filtrates and organic solvent extracts of over 500 freshwater and marine eukaryotic microalgae and cyanobacteria were screened for the presence of glycosidase inhibitors. Rapid colorimetric assays were used to detect inhibitors of alpha-glucosidase, alpha-amylase and beta-galactosidase. Inhibitors were found from 38 species. The results suggest that microalgae and cyanobacteria have potential as a source of glycosidase inhibitors which may have clinical applications.
J Gen Microbiol 1987 Jul
PMID:Microalgae and cyanobacteria as a source of glycosidase inhibitors. 311 66

The effect of the glucose analogue 5-thio-D-glucose (5TG) on the yeast Saccharomyces cerevisiae was studied. Derepression of mitochondrial respiratory chain cytochromes, alcohol dehydrogenase (isoenzyme II), NADH dehydrogenase and maltase was inhibited by 0.5-2 mM-5TG. Growth rate was only slightly affected. Ethanol was efficiently produced with 2 mM-5TG in medium initially containing 0.25% glucose. Mutants resistant to the growth inhibitory effects of 5TG on glycerol medium showed resistance to the catabolite repressing effects of glucose. Other mutants, known to be catabolite repression resistant, showed resistance to 5TG. The analogue seems to inhibit derepression of glucose repressible enzymes with greater potency than glucose itself.
J Gen Microbiol 1986 Dec
PMID:Catabolite repressive effects of 5-thio-D-glucose on Saccharomyces cerevisiae. 330 35

The mechanism of inactivation of hexokinase PII of Saccharomyces cerevisiae by D-xylose was characterized. Inactivation was dependent on the presence of MgATP and was irreversible. Inactivation involved phosphorylation of the protein. Observation of the carbon catabolite repression of selected enzymes showed that invertase and maltase synthesis were not repressed when hexokinase PII was phosphorylated.
J Gen Microbiol 1986 Dec
PMID:Mechanism of inactivation of hexokinase PII of Saccharomyces cerevisiae by D-xylose. 330 37

Both the MAL1 and MAL6 loci in Saccharomyces strains have been shown by functional and structural studies to comprise a cluster of at least three genes necessary for maltose utilization. They include regulatory, maltose transport and maltase genes designated MALR, MALT and MALS, respectively. Subclones of each gene derived from the MAL6 locus were inserted into the multicopy shuttle plasmid YEp13, introduced into MAL1 and mal1 strains and the effects of altered gene dosage of each gene, or a combination of them, on MAL gene expression investigated. MAL1 strains transformed with a plasmid carrying the MAL6S gene showed coordinate four to five fold increases in both maltase enzyme activity and its mRNA, whereas no increase in maltose transport activity or of MALT mRNA was observed when MAL6T was present on multicopy plasmids. The presence of the MAL6R gene on a multicopy plasmid led to greatly increased transcription of both inducible and constitutive mRNAs with homology to the regulatory gene; it also gave rise to two fold increases in both induced maltase mRNA levels and enzyme activity, but only in the presence of maltose. However, it had no apparent effect on the accumulation of MALT mRNA. Finally, the induction kinetics of plasmid-borne and chromosomal MALS and MALT gene expression were examined under conditions of altered gene dosage of the MAL6 regulatory and structural genes. The results of these experiments indicate that MALR encodes a trans-acting positive activator that requires maltose for induction of MALS and MALT transcription even when the regulatory gene is present on a multicopy plasmid. Maltose transport can be a rate-limiting factor in MAL gene expression, at least in the early stages of induction. The regulation of the MALS and MALT genes, whose activities are coordinately induced in MAL1 strains by maltose, may in fact exhibit some important differences.
Mol Gen Genet 1987 Oct
PMID:Regulation of MAL gene expression in yeast: gene dosage effects. 332 27

The role of hexokinase PII in mediating carbon catabolite derepression in yeast has been examined. Hexokinase isoenzyme PII (EC 2.7.1.1) was partially degraded when protease inhibitors were omitted from the buffer used for preparation of cell-free extracts. The hexokinase PII inactivation induced by D-xylose was correlated with derepression of maltase (EC 3.2.1.20) in the wild-type strain Saccharomyces cerevisiae G-517 and in D.308.3, a strain that contains the cloned hexokinase PII gene on a multicopy plasmid. This inactivation was not correlated with the loss of hexokinase PII protein as assayed by immunoblotting. We conclude that during the derepression process there is no release of proteolytic peptides from hexokinase PII.
J Gen Microbiol 1987 Sep
PMID:Proteolysis of hexokinase PII is not the triggering signal of carbon catabolite derepression in Saccharomyces cerevisiae. 332 14

A new mutation has been described which confers resistance to catabolite repression in Saccharomyces cerevisiae. The mutant allele, termed grr-1 for glucose repression-resistant, is characterized by insensitivity to glucose repression for the cytoplasmic enzymes invertase, maltase, and galactokinase, as well as the mitochondrial enzyme cytochrome c oxidase. Hexokinase levels in grr-1 mutants are approximately 3-fold higher than the corresponding activity of the parental strain. Although the grr-1 allele is expressed phenotypically similarly to the hex-1 (hxk-2) and hex-2 mutations described by Entian et al. (1977) and Zimmermann and Scheel (1977) respectively, we have shown genetically and physiologically that grr-1 represents a new class of mutation.
Mol Gen Genet 1984
PMID:Isolation and characterization of a pleiotropic glucose repression resistant mutant of Saccharomyces cerevisiae. 632 21

Each of at least five unlinked MAL loci (MAL1 through MAL4 and MAL6) on the yeast genome controls the ability to synthesize an inducible alpha-D-glucosidase (maltase). A subcloned fragment of the coding sequence of the MAL6 maltase structural gene was used as a hybridization probe to investigate the physical structure of the family of MAL structural genes in the genomes of different Saccharomyces strains. MAL+ strains, each carrying a genetically defined MAL locus, were crossed with a MAL- strain and the segregation behavior of the functional locus and of sequences complementary to the maltase structural gene at that locus analyzed. The maltase structural gene sequences of each MaL locus were detected by Southern blot hybridization using BamH1 digests of genomic DNA of the meiotic products. This restriction enzyme was previously shown to cleave outside the confines of the MAL 6 locus. The results of such experiments indicate that each MAL locus encompasses at least one maltase structural gene sequence homologous to that of MAL6, that yeast strains that lack functional MAL loci may or may not contain the corresponding maltase structural gene sequence, that the MAL1 maltase structural gene sequence or one of its alleles can be detected in all laboratory yeast strains examined and that each MAL locus can be identified as a characteristic BamH1 fragment of genomic DNA which includes a maltase structural gene. Yeast strains vary in the number of maltase structural gene sequences that they carry. By using the approach described in this report, the ones corresponding to the different functional MAL loci and residing within a BamH1 generated restriction fragment can be identified.
Mol Gen Genet 1983
PMID:Identification and physical characterization of yeast maltase structural genes. 635 59


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