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: KEGG:D00046 (lactose)
16,692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

beta-Galactosidase [EC 3.2.1.23] was isolated from a partially purified preparation obtained from cultured cells of a special strain of Aspergillus oryzae, RT 102 (FERM-P1680). The enzyme preparation gave a single protein band on polyacrylamide gel electrophoresis and was free from alpha-galactosidase, alpha- and beta-mannosidase, alpha- and beta-N-acetylhexosaminidase, and protease activities. The beta-galactosidase was capable of acting on aryl beta-galactosides, lactose, and lactosides. It also hydrolyzed beta-galactosyl linkages in urinary glycoasparagines and asialo alpha1-acid glycoprotein. The enzyme was rather stable in aqueous solution, retaining full activity at 4 degrees for at least several months. At pH 4.5, the optimum pH for the enzyme activity, and 37 degrees, full activity was maintained for several days.
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PMID:Characterization of beta-galactosidase from a special strain of Aspergillus oryzae. 1 18

beta-Galactosidase (EC 3.2.1.23) from fungus Curvularia inaequalis was modified by active brilliant orange KH and adsorbed on DEAE-Sephadex A-50. The lactose hydrolysis was studied in a continous flow on the column packed with the immobilized enzyme. The pH and temperatures optima for the substrate hydrolysis by the immobilized enzyme were shown to remain unchanged. A certain destabilizing effect of the matrix on the enzyme resistance to hear denaturation was observed. The activation parameters of denaturation of the native enzyme as well as those of the dye-modified and immobilized preparations were determined.
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PMID:[Enzymatic properties of immobilized beta-galactosidase from Curvularia inaequalis]. 1 60

A total of 191 Klebsiella pneumoniae isolates of human clinical, bovine mastitis, and a wide variety of environmental sources were tested for fecal coliform (FC) response with the membrane filtration and most probable number techniques. Twenty-seven Escherichia coli cultures of human clinical and environmental origins were also tested. Eighty-five percent (49/58) of known pathogenic K. pneumoniae were FC positive, compared with 16% (19/120) of the environmental strains. E. coli results indicated 93% (13/14) of the clinical and 85% (11/13) of the environmental strains as FC positive. There was no significant difference in the incidence of FC-positive cultures between pathogenic Klebsiella and E. coli. pH measurements of K. pneumoniae and E. coli cultures growing in m-FC broth at 44.5 degrees C revealed three distinct pH ranges correlating with colony morphology. beta-Galactosidase assays of Klebsiella and E. coli cultures at 44.5 degrees C indicated all were able to hydrolyze lactose, even if they were FC negative by the membrane filtration or most probable number techniques. The FC response pattern appears stable in K. pneumoniae. Three pathogenic cultures showed no change in FC responses after 270 generations of growth in sterile pulp mill effluent. Since K. pneumoniae is carried in the gastrointestinal tract of humans and animals and 85% of the tested pathogenic strains were FC positive, the isolation of FC-positive Klebsiella organisms from the environment would indicate their fecal or clinical origin or both. The added fact that K. pneumoniae is an opportunistic pathogen of increasing importance makes the occurrence of FC-positive environmental Klebsiella, particularly in large numbers, a potential human and animal health hazard.
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PMID:Significance of fecal coliform-positive Klebsiella. 1 86

Mutants of Escherichia coli have been isolated that are able to grow on lactose at pH 7.0 but not at pH 8.1. One of these mutants was analyzed and shown to map in the Z region of the lactose operon. beta-Galactosidase (beta-D-galactoside galactohydrolase; EC 3.2.1.23) activity in toluenized mutant cells at pH 8.0 was one-tenth that at pH 7.0. Enzyme purified to near homogeneity from the pH-conditional mutant similarly exhibited pH-conditional activity under conditions where wild-type enzyme was unaffected over a pH range of 6.0-8.0. The pH-conditional beta-galactosidase was used in vivo as a probe for intracellular pH. We show that an internal pH of approximately 7.8-8.0 is maintained through an external pH range of 5.9-7.8. The phenotype of pH-conditional mutants was defined on medium with lactose as the sole carbon source. Under such conditions the gene product itself, beta-galactosidase, is required to maintain intracellular pH, since such maintenance is clearly energy-dependent. Therefore, we were able to recover a pH-conditional mutant in a cytoplasmic gene product. We predict that with any phenotype independent of energy production, however, pH-sensitive mutants will be recovered only in surface elements.
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PMID:A pH-conditional mutant of Escherichia coli. 2 35

beta-Galactosidase (EC 3.2.1.32) was purified 80-fold from the yeast Kluyveromyces lactis induced for this enzyme by growth on lactose. When the purified enzyme was subjected to electrophoresis on an acrylamide gel in the presence of sodium dodecyl sulfate, one protein with an apparent molecular weight of 135,000 was observed. The enzyme has a sedimentation coefficient of 9.6S. This beta-galactosidase and the one from Escherichia coli are not antigenically related. Maximal enzyme activity requires Na+ and Mn2+ and a reducing agent. beta-Galactosidase has Km values of 12 to 17 and 1.6 mM for lactose and o-nitrophenyl-beta-D-galactoside, respectively. The hydrolase and transgalactosylase activities of the enzyme are similar to those of E. coli beta-galactosidase.
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PMID:Purification and properties of an inducible beta-galactosidase isolated from the yeast Kluyveromyces lactis. 3 53

A clinical description of an apparently classical case of type 1 GM1 gangliosidosis is presented. The patient was the first-born child of first cousins. She was diagnosed at 6 weeks and died at 6 months. beta-Galactosidase activity was deficient in cultured fibroblasts using [3H]GM1 ganglioside and [3H]ceramide-lactose as substrates. Genetic complementation studies performed after cell fusion between cultured fibroblasts from the patient and from two other type 1, one type 2, and one juvenile GM1 gangliosidosis strain were positive with all strains. Subsequent studies revealed an increased excretion of a sialic acid-containing hexasaccharide in the patient's cells. Parents' fibroblasts contained normal levels of beta-galactosidase. The case emphasizes the variability of the clinical expression in sialidosis and the importance of demonstrating a primary gene defect in establishing a diagnosis of an inborn error or metabolism.
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PMID:Infantile sialidosis: a phenocopy of type 1 GM1 gangliosidosis distinguished by genetic complementation and urinary oligosaccharides. 11

Sublethal stress in Escherichia coli was detected in various test media after exposure (in vitro) to seawater of various salinites. Stress was measured with an electrochemical detection technique and a beta-galactosidase assay. Test media included EC medium, medium A-1, and tryptic soy broth modified to contain lactose for beta-galactosidase assay experiments. Stress was defined as the difference between a predicted electrochemical response time calculated for unstarved cells from a standard curve and the observed electrochemical response time for cells starved in seawater. The higher the salinity, the greater the stress for all test media examined. Stress was most pronounced in EC and was attributed primarily to initial die-off of starved cells exposed to the test medium at the elevated temperature of 44.5 degrees C. Lag time and growth rates in test media were not significantly affected by salinity. beta-Galactosidase specific activity, assayed in starved cells after transfer to an induction medium at 44.5 degrees C for 150 min, was inversely related to the salinity of the starved cell suspension. The consequences of these observations with respect to coliform enumeration methods are discussed.
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PMID:Sublethal stress in Escherichia coli: a function of salinity. 11 8

The expression of cell cycle events in Caulobacter crescentus CB13 has been shown to be associated with regulation of carbohydrate utilization. Growth on lactose and galactose depends on induction of specific enzymes. Prior growth on glucose results in a delay in enzyme expression and cell cycle arrest at the nonmotile, predivisional stage. Dibutyryl cyclic adenosine 3',5'-monophosphate (AMP) was shown to stimulate expression of the inducible enzymes and, thus, the initiation of the cell cycle. beta-Galactosidase-constitutive mutants did not exhibit a cell cycle arrest upon transfer of cultures from glucose to lactose. Furthermore, carbon source starvation results in accumulation of the cells at the predivisional stage. The cell cycle arrest therefore results from nutritional deprivation and is analogous to the general control system exhibited by yeast (Hartwell, Bacteriol. Rev. 38:164-198, 1974; Wolfner et al., J. Mol. Biol. 96:273-290, 1975), which coordinates cell cycle initiation with metabolic state. Transfer of C. crescentus CB13 from glucose to mannose did not result in a cell cycle arrest, and it was demonstrated that this carbon source is metabolized by constitutive enzymes. Growth on mannose, however, is stimulated by exogenous dibutyryl cyclic AMP without a concomitant increase in the specific activity of the mannose catabolic enzymes. The effect of cyclic AMP on growth on sugars metabolized by inducible enzymes, as well as on sugars metabolized by constitutive enzymes, may represent a regulatory system common to both types of sugar utilization, since they share features that differ from glucose utilization, namely, temperature-sensitive growth and low intracellular concentrations of cyclic guanosine 3',5'-monophosphate.
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PMID:Effect of carbon source and the role of cyclic adenosine 3',5'-monophosphate on the Caulobacter cell cycle. 19 60

Vectors containing fusions of the Candida albicans ACT promoter to heterologous genes were constructed and transformed into a C. albicans host strain. beta-Galactosidase (Lac4p) activity was detected in transformants carrying an ACT fusion to the Kluyveromyces lactis LAC4 gene, while fusions to the Escherichia coli lacZ gene and to other heterologous genes were not expressed. Lac4p was also produced by C. tropicalis transformants carrying the ACT/LAC4 fusion. Plasmids in transformed C. albicans strains were present either as free multimers in high copy number or, more frequently, integrated into the genome in low copy number yielding high and low LAC4 mRNA and Lac4p expression levels, respectively. Lac4p-expressing transformants of C. tropicalis, but not of C. albicans, were able to utilize lactose as sole carbon source. An ACT/LAC4 fusion was not differentially expressed during the yeast and hyphal growth phases of C. albicans, indicating that the ACT promoter is not regulated during morphogenesis. These results define the first reporter gene system for convenient monitoring of gene expression in Candida species.
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PMID:beta-Galactosidase of Kluyveromyces lactis (Lac4p) as reporter of gene expression in Candida albicans and C. tropicalis. 146 97

The activity of the mucosal beta-galactosidase of caecum and colon is low in both germfree and conventional rats. beta-Galactosidase activity occurs also in the chymus of germfree rats. It increases after monoassociation and is higher in conventional than in germfree animals. Lactose entering caecum and colon acts like dietary fibre and is hydrolysed mainly by the intestinal flora. Aerobe lactobacilli and bacteroides predominate in the microflora of rat caecum and colon. A lactose-containing diet increases the total number of germs and stimulates the growth of bifidobacteria. After special diets, rich in lactose and low in protein and phosphate (e.g. human milk and similar formulae), the number of bacteroides and other putrefactive germs decreases. Moreover, a lactose-containing diet alters the metabolic activity of intestinal microorganisms (activity of microbial beta-galactosidase, acidification and lowering of ph in the chymus, production of hydrogen, proteolytic activity.) Lactose as dietary fibre decreases the nitrogen excretion in the urine and increases the N-excretion in the faeces of conventional rats.
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PMID:[Lactose--a potential dietary fiber. The regulation of its microecologic effect in the intestinal tract. 3. Dietary fiber actions of lactose due to microbial activity]. 166 42


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