Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We review and update the work on genetic elements, e.g., viruses and plasmids (exluding IS elements and transposons) in the kingdom Crenarchaeota (Thermoproteales and Sulfolobales) and the orders Thermococcales and Thermoplasmales in the kingdom Euryarchaeota of the archael domain, including unpublished data from our laboratory. The viruses of Crenarchaeota represent four novel virus families. The Fuselloviridae represented by SSVI of S. shibatae and relatives in other Sulfolobus strains have the form of a tailed spindle. The envelope is highly hydrophobic. The DNA is double-stranded and circular. Members of this group have also been found in Methanococcus and Haloarcula. The Lipothrivciridae (e.g., T TV1 to 3) have the form of flexible filaments. They have a core containing linear double-stranded DNA and DNA-binding proteins which is wrapped into a lipid membrane. The "Bacilloviridae" (e.g., TTV4 and SIRV) are stiff rods lacking this membrane, but also featuring linear double-stranded DNA and DNA-binding proteins. Both virus types carry on both ends structures involved in the attachment to receptors. Both types are represented in Thermoproteus and Sulfolobus. The droplet-formed novel Sulfolobus virus SNDV represents the "Guttaviridae" containing circular double-stranded DNA. Though head and tail viruses distantly resembling T phages or lambdoid phages were seen electronmicroscopically in solfataric water samples, no such virus has so far been isolated. SSV1 is temperate, TTV1 causes lysis after induction, the other viruses found so far exist in carrier states. The hosts of all but TTV1 survive virus production. We discuss the implications of the nature of these viruses for understanding virus evolution. The plasmids found so far range in size from 4.5 kb to about 40 kb. Most of them occur in high copy number, probably due to the way of their detection. Most are cryptic, pNOB8 is conjugative, the widespread pDL10 alleviates in an unknown way autotrophic growth of its host Desulfurolobus by sulfur reduction. The plasmid pTIK4 appears to encode a killer function. pNOB8 has been used as a vector for the transfer of the lac S (beta-galactosidase) gene into a mutant of S. solfataricus.
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PMID:Viruses, plasmids and other genetic elements of thermophilic and hyperthermophilic Archaea. 863 30

An investigation of beta-galactosidase activity of Escherichia coli strain H10407, under different physiological and environmental conditions, e.g. induced and uninduced osmotic stress, light, etc., was undertaken. In this study E. coli was employed as a model for faecal coliforms in waste water. beta-Galactosidase activity was induced by isopropyl-beta-D-thiogalactoside (IPTG). Enzyme activity (U cell-1)/cell for sewage bacteria and for induced E. coli was similar, i.e. log U cell-1 = -8.5 whereas uninduced E. coli yielded log U cell-1 = -12.1. Initial enzyme activity was not dependent on phase of growth of the cell (exponential vs stationary phase) or whether marine or fresh water at the time of initial dilution. However, osmotic change resulted in a decrease in culturable cells, even though enzyme activity remained constant. A significant decrease in the number of culturable bacteria, followed by a decrease in beta-galactosidase activity, was observed after exposure of cells to visible light radiation. It is concluded that beta-galactosidase enzyme is retained in viable but non-culturable E. coli. Furthermore, beta-galactosidase appears to offer a useful and rapid (25 min) measure of the viability of faecal coliforms, and therefore, of the water quality of bathing and shellfishing areas.
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PMID:Effect of seawater on Escherichia coli beta-galactosidase activity. 876 Mar 26

The glycerol phosphate shuttle consists of FAD-linked mitochondrial glycerol 3-phosphate dehydrogenase (mGPDH) and its cytosolic NAD-linked isoform (cGPDH). Impaired mGPDH activity has recently been suggested to be one of the primary causes of insulin secretory defects in beta-cells. We found that mGPDH and cGPDH activities in MIN6 cells are comparable to those of isolated islets and higher than those in HIT cells by eightfold and threefold, respectively. Therefore, we selected the MIN6 cell line as a beta-cell model with normally regulated insulin secretion and normal shuttle enzyme activities and the HIT cell line as a beta-cell model with impaired insulin secretion and lower activities of these enzymes. The role of these dehydrogenases in glucose-stimulated insulin secretion was addressed by examining the effects of overexpression of mGPDH and/or cGPDH via recombinant adenoviruses in these cells. Infection with recombinant adenovirus with a cDNA encoding the Escherichia coli beta-galactosidase gene resulted in expression of its gene in 90% of MIN6 and HIT cells. Infection with a recombinant adenovirus with mGPDH cDNA (Adex1CAmGPDH) caused 2.1-fold and 5.7-fold increases in dehydrogenase activity as compared with those of control MIN6 and HIT cells, respectively. Infection with a recombinant adenovirus with cGPDH cDNA (Adex1CAcGPDH) caused a more than 50-fold increase in activity in both cell lines. Glycerol phosphate shuttle flux, as estimated by [2-3H]glycerol conversion to [3H]H2O, was increased to 120-130% by infection with Adex1CAmGPDH, but not with Adex1CAcGPDH infection, in both MIN6 and HIT cells. No further increase in flux through the glycerol phosphate shuttle was detected when the cells were infected with Adex1CAmGPDH together with Adex1CAcGPDH. Furthermore, neither [U-14C]glucose oxidation nor the insulin secretory response to glucose was affected in either cell line. Thus, mGPDH abundance in MIN6 and HIT cells is not directly related to their insulin secretory capacity in response to glucose, and reduced expression of mGPDH is not the primary cause of abnormal insulin secretory responses in HIT cells. The present data indicate that the emerging hypothesis pointing to mGPDH deficiency as a possible cause of NIDDM needs to be carefully evaluated.
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PMID:Effect of mitochondrial and/or cytosolic glycerol 3-phosphate dehydrogenase overexpression on glucose-stimulated insulin secretion from MIN6 and HIT cells. 877 29

Second-order rate constants for transfer of the beta-D-galactopyranosyl group from the galactosyl-enzyme intermediates of the galactosyl transfer reactions catalyzed by E461G and E461Q beta-galactosidases to anionic nucleophiles have been determined. The second-order rate constant for reaction of the galactosylated E461G enzyme with azide ion is 4900 M-1 s-1. By contrast, there is no detectable reaction of the galactosylated wild type enzyme with azide ion (Richard et al., 1995b), and the E461G mutation leads to a large decrease in the second-order rate constant kcat/Km for catalysis of cleavage of beta-D-galactopyranosyl azide, which is the microscopic reverse of the reaction of azide ion with the galactosyl-enzyme intermediate. These data show that the E461G mutation causes a more than 8000-fold increase in the equilibrium constant for transfer of the beta-D-galactopyranosyl group from beta-galactosidase to azide ion. We propose that this change represents the requirement for the coupling of galactosyl transfer from the native enzyme to the thermodynamically unfavorable protonation of the carboxylate group of Glu-461, but the expression of the full chemical affinity of azide ion for galactosyl transfer from the mutant enzyme which lacks this ionizable side chain at position 461. The reactions of acetate, butyrate and methoxyacetate ions with the galactosylated E461G enzyme and of acetate with the galactosylated E461Q enzyme give both the corresponding beta-galactopyranosyl derivatives and D-galactose, and the formation of the latter represents formal catalysis of the reaction of water with the galactosylated enzyme. However, the reaction of formate ion with the galactosylated E461G enzyme gives only D-galactose. These results suggest that carboxylate anions can take the place of the excised propionate side chain of Glu-461 to provide general base catalysis of the reaction of water with the galactosyl-enzyme intermediates. The relative reactivity of anionic nucleophiles toward the covalent galactosyl-enzyme intermediate of the reactions catalyzed by the E461G enzyme is similar to that observed for partitioning of stable carbocations in water. This suggests that replacement of the anionic side chain of Glu-461 by a hydrogen exposes an enzyme-stabilized oxocarbenium ion intermediate to reaction with external nucleophilic reagents.
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PMID:Structure-reactivity relationships for beta-galactosidase (Escherichia coli, lac Z). 4. Mechanism for reaction of nucleophiles with the galactosyl-enzyme intermediates of E461G and E461Q beta-galactosidases. 882 74

A method to concentrate drugs, DNA, or other materials with target cells in two-phase polymer systems for high-efficiency electroloading is described. The two-phase polymer system is utilized for cell and loading material selection, as well as for cell aggregation before electrofusion. The phase mixing of several water-soluble polymers is characterized, and the polyethylene glycol-Dextran (PEG m.w. 8,000 + Dextran m.w. 71,000) mixture is selected to illustrate the advantage of the two-phase systems. Fluorescently labeled Dextran or DNA is loaded into Chinese hamster ovary (CHO) and JTL cells, using electroporation in either the two-phase polymer system or the conventional single-phase suspension. The loading efficiency is 4 to 30 times higher for the two-phase system, with the best advantage at lower applied field range. Transfections of CHO, COS, Melan C, and JTL lymphoid cells using pSV-beta-galactosidase (for CHO and COS), pBK-RSV-tyrosinase, and pCP4-fucosidase plasmids, respectively, by electroporation in the two-phase polymer system and the conventional single-phase electroporation method, are compared. The former method is far superior to the latter in terms of efficiency. The threshold and optimal field strengths for the former are significantly lower than those for the latter method, so the former method is more favorable in terms of equipment requirement and safety. Electrofusion efficiency in the two-phase system is comparable to that in polyethylene glycol suspension alone and is a significant improvement from the conventional electrofusion method with dielectrophoresis. The two-phase polymer method is, therefore, a valuable technique for gene delivery to a limited cell source, as in ex vivo gene therapy.
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PMID:High-efficiency loading, transfection, and fusion of cells by electroporation in two-phase polymer systems. 884 49

Evidence for temporal variations in the nephrotoxicity of low doses of aminoglycosides were recently shown by using specific and sensitive parameters of renal toxicity. The aim of the present study was to evaluate the effect of a short period of fasting on the temporal variations in the renal toxicity of gentamicin. Twenty-eight normally fed (i.e., food and water were available ad libitum throughout the experiment) female Sprague-Dawley rats (weight, 175 to 220 g) and 28 fasted rats (i.e., only water was available during a 12-h fast before and a 24-h fast after gentamicin injection) were used. The animals were synchronized on a 14-h light, 10-h dark cycle (lights on at 0600 h) for 1 week before gentamicin administration. In July 1993, each group of animals was treated with a single intraperitoneal injection of saline (NaCl, 0.9%) or gentamicin (150 mg/kg of body weight) at either the peak (1400 h) or the trough (0200 h) of the previously determined toxicity. On day 1, the 24-h urinary excretion of beta-galactosidase, N-acetyl-beta-D-glucosaminidase, and gamma-glutamyltransferase was significantly higher in normally fed animals treated with gentamicin at 1400 h than in their time-matched controls and in normally fed animals treated at 0200 h (P < 0.01), which had normal levels of these enzymes. By contrast, the urinary excretion of these enzymes was significantly higher in both groups of gentamicin-treated, fasted rats than in their time-matched control groups (P < 0.01), reaching levels similar to those measured in normally fed rats treated at 1400 h. The accumulation of gentamicin was significantly lower in the renal cortex of normally fed rats treated at 0200 h than in rats treated at 1400 h (P < 0.05), but this time-dependent difference was not found in fasted rats treated at 0200 and 1400 h. Immunogold labeling done on ultrathin sections and observed by electron microscopy showed a similar subcellular localization of gentamicin in normally fed and fasted rats treated at either 1400 or 0200 h. These results suggest that the feeding period is of crucial importance in the temporal variations of the nephrotoxicity of gentamicin in rats.
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PMID:Effects of fasting on temporal variations in nephrotoxicity of gentamicin in rats. 885 91

Various models of the transmembrane topology of the Na+,K+-ATPase predict either 8 or 10 membrane spans for the alpha-subunit and one to three membrane spans for the beta-subunit. Structure/function analysis, however, requires precise knowledge about the folding of enzymes. Therefore, the intention of this work was to establish a transmembrane topology model for the subunits of Na+,K+-ATPase. The bacterial enzyme beta-galactosidase was fused to the C termini of truncated alpha- and beta-subunits of Na+,K+-ATPase. Fusions were generated at Arg60 (LTTAR60), Glu116 (AATEE116), Ala247 (VEGTA247), Leu311 (YTWEL311), Ala444 (VAGDA444), Ala789 (IFIIA789), Met809 (LGTDM809), Asp884 (RVTWD884), Ile946 (MKNKI946), and Arg972 (GVALR972) of the sheep alpha1-subunit and at Pro236 (LGGYP236) of the dog beta-subunit. The fusion constructs were expressed in yeast cells for studies on the localization of the fused reporter enzyme. Activity measurements of the reporter enzyme revealed that only intracellular fusion sites lead to active beta-galactosidase. Indirect immunofluorescence microscopy with cells expressing alpha1/beta-galactosidase and beta/beta-galactosidase hybrid proteins demonstrated that inactive beta-galactosidase is associated with the yeast plasma membrane and can be detected from the extracellular side. The data obtained suggest that Pro236 of the beta-subunit is located on the extracellular surface, corresponding to a model with one transmembrane segment, and that the alpha-subunit of the Na+,K+-ATPase consists of 10 membrane-associated spans. They also suggest that a stretch of the alpha1-subunit between membrane spans M7 and M8 might be hidden within the membrane, surrounded by the other hydrophobic spans, in analogy to the P-loop of Na+ or K+ channels and to the "hourglass" structure of water channels.
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PMID:Transmembrane topology of alpha- and beta-subunits of Na+,K+-ATPase derived from beta-galactosidase fusion proteins expressed in yeast. 891 May 92

Diffuse invasion of brain tissue by single tumor cells is a characteristic feature of gliomas and a major reason why these tumors cannot be completely resected. The molecular basis of brain invasion is poorly understood. We regulated the expression of beta 1 integrins, the major group of extracellular matrix receptors, in astrocytic tumor cells by using a tetracycline-dependent transcription control system. Rat C6 glioma cells were stably transfected with (a) the tetracycline-controlled transactivator (tTA) gene, (b) antisense beta 1 cDNA under the control of a tTA/tetracycline-responsive promoter, and (c) the beta-galactosidase (lacZ) gene for histochemical identification. In one clone, C6TL beta, beta 1 protein levels were unaffected in the presence of tetracycline, but they were reduced by 60% in the absence of tetracycline because of production of antisense mRNA. C6TL beta cells were transplanted into the striatum of nude mice. After 14 days in the presence of tetracycline in the drinking water, tumors showed diffuse brain invasion, mainly along vascular basement membranes. In the absence of tetracycline, however, tumor cells were compact and generally well delineated from the surrounding brain tissue. These data, ie, blocking of brain invasion by antisense beta 1 mRNA, either because of disturbed interaction of beta 1 with brain extracellular matrix components or interference with beta 1-dependent signaling pathways, strongly suggest that beta 1 integrins are required for diffuse brain invasion of gliomas.
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PMID:Diffuse brain invasion of glioma cells requires beta 1 integrins. 897 77

Transgenic strains of the nematode Caenorhabditiselegans, which carry stress-inducible lacZ reporter genes, aremeasurably stressed by exposure to heavy metals in aqueous solution. Thisstress response can be quantified, using enzymatic assays for the reportergene-product (Escherichia coli beta-galactosidase), or estimatedapproximately by in situ staining for beta-galactosidase in exposedworms. Stress responses to heavy metals have been demonstrated both inlaboratory tests using Cd2+ or Hg2+, and also in watersamples taken from a metal-polluted river system in southwest England. TheRiver Carnon flows through an area with an ancient mining history,principally for Sn, but also for Cu and other metals; As, Cd, Al, Mn, and Zn,as well as large amounts of Fe, are all present in these ore bodies. Foursites in the Carnon river basin were compared with respect to theirmacroinvertebrate diversity, physical and chemical characteristics (includingthe concentrations of As, Cd, Al, Cu, Mn, Zn, and Fe). Transgenic worms wereexposed to water samples from these four sites, and also to a 0.33%(v/v) dilution of metal-laden minewater from the principal local mine (WhealJane). Transgene expression was induced in all five cases, though markedlyless so for the least polluted of the sites (which also supported a richermacroinvertebrate fauna). Two different transgenic strains were tested inthis study; strain PC72 (using a homologous hsp16 promoter) isslightly more sensitive to most metal-containing water samples than strainCB4027 (using a heterologous Drosophila hsp70 promoter). Bothtransgenic strains and two different assay methods gave essentially similarresults. These findings demonstrate that transgenic nematodes could provide arapid and simple assessment of aquatic pollution, in that the transgeneresponse is inducible by mixtures of dissolved metals at concentrationsactually encountered in metal-polluted watercourses.
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PMID:Use of stress-inducible transgenic nematodes as biomarkers of heavy metal pollution in water samples from an english river system. 906 89

Four field strains of Lactobacillus plantarum (LS 4, 19, 21, 133) obtained from fufu (a semi-solid product obtained by boiling fermented cassava--Manihot esculenta Crantz) and a type strain DSM 2017 were grown on different carbon sources to induce galactosidase production. LS 21 produced the highest concentration of alpha- and beta-galactosidase with 0.28 mumol/l and 0.28 mumol/l respectively on lactose and galactose. Milk obtained from soybean seeds treated with the enzyme mixture for 24 h showed a 99, 98 and 96% reduction respectively in the raffinose, stachyose and sucrose content when compared with the dry soybean seed. Glucose and galactose which were not detected in the dry seeds became readily available after soaking in both enzyme mixture and distilled water. Although there was reduction in the nutritional composition of both milk samples, reduction of phytic acid and trypsin inhibitor is beneficial to the consumers. The result of the sensory evaluation showed that the milk prepared from enzyme-treated soybean seeds was rated better in terms of flavour, texture, appearance and palatability.
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PMID:Effect of bacterial galactosidase treatment on the nutritional status of soybean seeds and its milk derivative. 911 67


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