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)

The gal3 mutation of Saccharomyces, which is associated with an impairment in the utilization of galactose, has been shown to be pleiotropic, causing similar impairments in the utilization of melibiose and maltose. Milibiose utilization and alpha-galactosidase production are directly controlled by the galactose regulatory elements i, c, and GAL4. The fermentation of maltose and the induction of alpha-glucosidase are regulated independently of the i, c, GAL4 system. The production of alpha-galactosidase and galactose-1-phosphate uridyl transferase is coordinate in galactokinaseless strains. Galactose serves as a nonmetabolized, gratuitous inducer of alpha-galactosidase in strains lacking the genes for one or more of the Leloir pathway enzymes.
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PMID:Genetic co-regulation of galactose and melibiose utilization in Saccharomyces. 124 60

The present work investigates the ability of galactose to affect enterocyte differentiation during normal development in vivo. Energy intake has also been varied to take account of the fact that galactose is poorly metabolized in mice. Brush-border lactase, alpha-glucosidase, dipeptidylpeptidase-IV, aminopeptidase N, alkaline phosphatase and microvillus length were measured as markers of enterocyte differentiation in mice fed diets containing galactose (G diet), corn oil (E diet) or galactose + corn oil (G + E diet). Maintaining mice on a G instead of E diet reduced brush-border lactase activity and enterocyte migration rates; alpha-glucosidase, dipeptidylpeptidase-IV, aminopeptidase N and microvillus length expression increased and alkaline phosphatase activity remained unchanged. Feeding the G + E diet restored enterocyte migration rates, lactase, aminopeptidase N and dipeptidylpeptidase-IV activities to values found in mice fed the E diet. Galactose stimulation of alpha-glucosidase and microvillus length expression was, however, fully maintained in mice fed the G + E diet. Present results show that enterocyte differentiation is affected independently by varying dietary galactose and energy levels; that galactose effects always increase and energy effects usually decrease expression of enterocyte components and that energy stimulation of lactase activity is exceptional.
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PMID:Galactose effects on enterocyte differentiation in the mouse jejunum. 190 92

Present work uses a combination of quantitative cytochemistry and measurements of cell migration rates to describe galactose effects on lactase expression by mouse enterocytes. Mice fed galactose were found to eat less, weigh less and drink more than mice maintained on a low-carbohydrate isocalorific diet. The enterocyte migration rate in these mice was also only one third of that determined in low-carbohydrate-fed animals. The rate at which lactase activity increased in the brush border membrane of migrating enterocytes was 3-times greater in low-carbohydrate- compared with galactose-fed mice. The time during which this increase persisted was, however, 3-times less in low-carbohydrate-fed animals. The maximum rate of sucrase-maltase appearance, measured as control in these experiments, remained unaffected by galactose feeding. Galactose effects on lactase expression might in part result from mice being unable to metabolise this substrate. Previously it has been stated that galactose increases lactase biosynthesis in rat intestine (Koldovsky, O., Bustamonte, S. and Yamada (1981) In Mechanisms of intestinal adaptation (Robinson, J.W.L., Dowling, R.H. and Ricken, E.O., eds.), pp. 153-156, MTP Press, Lancaster). This result is discussed in relation to the opposite finding reported in the present work for mouse jejunal enterocytes. The need to relate enzyme appearance to age and developmental state of enterocytes in this type of study is also emphasized.
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PMID:Galactose inhibits lactase expression by mouse jejunal enterocytes. 210 3

The effect of supplementation of the diet with galactose on the age-related decline of intestinal lactase activity was investigated in 108 growing rats. Starting from 14 days of age, the rats were divided into two groups and fed with chow, and with fluid either as tap water or 5% galactose solution. At 14 days the specific lactase activity was 112.8 +/- 3.2 mumol min-1 (g protein)-1, which decreased to less than 10% of this value at maturity. Galactose supplementation did not prevent the decline. The increase of maltase, sucrase and trehalase was also unaffected. The result suggests that galactose plays no significant role in the regulation of disaccharidase activities in the rat.
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PMID:The effect on intestinal disaccharidase activity of feeding galactose to growing rats. 224 21

The long-term (28 days) effects of feeding two glucocorticoids, prednisolone and betamethasone 17-valerate, on the adult rat jejunum were examined. Both steroids increased the activities of microvillus enzymes, alpha-glucosidase, aminopeptidase, and gamma-glutamyltransferase, measured in isolated epithelial cells by 46-83%. However, betamethasone 17-valerate caused striking epithelial hypoplasia such that microvillus enzyme activity per centimeter of intestine was similar to that of control rats. Prednisolone produced a trivial epithelial hypoplasia, and therefore microvillus enzyme activity per centimeter of intestine was increased. D-Galactose absorption measured in vivo was similarly affected by the two steroids. D-Galactose absorption per centimeter of intestine was increased after prednisolone but unchanged after betamethasone 17-valerate. Thus, glucocorticoids have separate and opposing actions on the function and structure of the adult rat small intestine: a) to increase the digestive-absorptive function of the mature epithelial cell and b) to decrease the epithelial cell population. These findings suggest that the effect of any particular glucocorticoid on intestinal function will depend on the extent to which these opposing actions predominate.
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PMID:Differential effect of glucocorticoids on structure and function of adult rat jejunum. 611 32

Hexose-phosphorylating enzymes from the starch-utilizing yeast Schwanniomyces occidentalis were purified and two isoenzymes separated. The substrate pattern characterized one of these as a hexokinase phosphorylating glucose and fructose and the other as a glucokinase unable to phosphorylate fructose. The purified Schw. occidentalis hexokinase had a KM value of 0.98 mM for glucose and 9.3 mM for fructose. The hexokinase gene was cloned by cross hybridization with a probe from the Saccharomyces cerevisiae HXK2 gene. Deletion of Schw. occidentalis hexokinase by gene replacement yielded a mutant unable to grow on fructose as sole carbon source, but still growing on glucose. Deletion mutants of Schw. occidentalis hexokinase prevented glucose repression of invertase and maltase. Growth deficiencies and the defect of glucose repression of a S. cerevisiae hexokinase null mutant could be restored by heterologous expression of the Schw. occidentalis hexokinase. Moreover, the results clearly showed the existence of a separate glucokinase in Schw. occidentalis.
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PMID:Molecular and biochemical characterization of the hexokinase from the starch-utilizing yeast Schwanniomyces occidentalis. 761 56

A set of two episomal yeast expression vectors, pYME1 and pYME2, were constructed. These Saccharomyces cerevisiae-Escherichia coli shuttle vectors each contain a modified yeast MAL6S (encoding maltase) promoter that is expressed constitutively, but is subject to carbon catabolite repression by glucose. Expression from this promoter is still dependent upon the presence of active MALR (regulatory) protein. These expression vectors are particularly useful because most S. cerevisiae strains are MAL+, thereby exhibiting a wider host range than GAL-based vector systems. These pYME1 and pYME2 vectors are capable of expression to levels comparable to GAL-based expression plasmids and much higher than a variety of other repressible promoter vectors. The vectors are identical, except that their multiple cloning sites (MCS) are in opposite orientations, making them convenient for inserting heterologous genes.
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PMID:Construction of glucose-repressible yeast expression vectors. 829 51

The goal of this study was to assess the contributions of the most important acid glycosidases to the processes connected with testes involution (in the summer) and spermatogenesis during the reproductive season (the spring) in ganders. Statistically significant increases in the specific activity of N-acetyl-beta-D-hexosaminidase, alpha-D-galactosidase, beta-D-galactosidase, and alpha-L-fucosidase during the period of testes involution were detected. Alpha-D-galactosidase, beta-D-galactosidase, and alpha-D-glucosidase showed an increase in the relative contribution of those multiple forms which are characterized by less acidic values of the pI during the reproductive season. It is suggested that the observed increases in the specific activity of beta-HEX, alpha-GAL, beta-GAL and alpha-FUC may be connected with the catabolism of glycoconjugates, when the spermatogenic activity of the testes declines. The increases in the relative contribution of less acidic forms of alpha-GAL, beta-GAL, and alpha-GLU during the reproductive season may be linked to the rise in the number of spermatocytes, spermatids and spermatozoa during spermatogenesis.
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PMID:Sesonal changes in acid glycosidases from gander testes. 1112 69

Activities of seven acid glycosidases: beta-N-acetylhexosaminidase (beta-HEX), alpha- and beta-galactosidase (alpha- and beta-GAL), alpha- and beta-mannosidase (alpha- and beta-MAN), alpha-glucosidase and alpha-fucosidase in magnum region of hen (Gallus gallus domesticus) oviduct, and four acid glycosidases: beta-HEX, beta-GAL, alpha- and beta-MAN in egg albumen, were investigated. beta-HEX from magnum and egg albumen hydrolysed 4-methylumbelliferyl-beta-N-acetylhexosamine-6-sulphate (4-MeUmbGlcNAc-6-SO(4)) like mammalian beta-HEX form A. Multiple forms of magnum and egg albumen beta-HEX, beta-GAL, alpha- and beta-MAN were separated by strong anion exchange chromatography and chromatofocusing method. Chromatofocusing of the magnum resulted in the appearance of multiple forms for beta-HEX with pI of 6.18, 5.43, 5.55, 5.34, 5.27 and 5.16, for beta-GAL with pI of 4.98, 4.84, 4.77, 4.64 and 4.68-4.63, for alpha-MAN with pI of >or=7.4, 6.75, 6.62 and 6.26, and for beta-MAN two forms with pI of 6.37 and 5.77. Chromatofocusing of egg albumen yields multiple forms for beta-HEX with pI of 6.24, 6.08, 5.55 and 5.35, for beta-GAL two forms with pI of 5.10 and 4.86-4.80 for alpha-MAN multiple forms with pI of >or=7.4, 6.80, 6.60 and 6.30, and for beta-MAN forms with pI of 6.30 and 5.77. In conclusion, this study was the first to show beta-HEX activity against 4-MeUmbGlcNAc-6-SO(4) in the magnum and albumen of bird eggs, corresponding to beta-HEX A activity in mammals. Main multiple forms of beta-HEX, beta-GAL, alpha- and beta-MAN occurring in the magnum were revealed in the egg albumen. Comparison with a cock of the same breed showed that hen egg magnum and albumen has the same multiple forms of the enzymes that are found in the epididymides and seminal plasma of the cock.
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PMID:Acid glycosidases from hen oviduct and egg albumen. 1623 36

The C7N-cyclitol containing alpha-glucosidase inhibitor acarbose is commercially produced using developed strains of Actinoplanes and is used in the treatment of patients suffering from diabetes type II. We have identified a second acarbose production cluster using a genomic cosmid gene bank from Streptomyces glaucescens GLA.O and sequenced a region (42658bp; accession AM409314) which clearly contained a gene cluster (gac-cluster) for the synthesis of acarbose or acarbose related endproducts. The gac-cluster exhibited large similarities to the acb-gene cluster from Actinoplanes. However, remarkable differences are found in the biosynthesis of the C7N-cyclitol in the two acarbose biosynthesis pathways. We show the expression of selected genes using RT-PCR approaches, we were able to detect small amounts of acarbose or acarbose related metabolites and we have characterized the GacK protein, an acarbose kinase, which specifically phosphorylates acarbose and acarbose homologs. All these data in combination with the postulated functions of the encoded Gac proteins clearly indicate that also in S. glaucescens a recycling mechanism for acarbose ("carbophor") which had been described for the first time for acarbose cluster from Actinoplanes, is also realised.
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PMID:The gac-gene cluster for the production of acarbose from Streptomyces glaucescens GLA.O: identification, isolation and characterization. 1905 89


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