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:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Zymomonas mobilis alcohol dehydrogenase II gene (adhB) was overexpressed 7- to 14-fold on a recombinant plasmid, accompanied by a small decrease in growth rate. A fragment containing the truncated gene with promoter reduced expression from the chromosomal gene as measured immunologically and enzymatically, consistent with the presence of a trans-active regulatory factor and positive regulatory control. Both the complete gene and the promoter fragment increased pyruvate decarboxylase and glucokinase activities, with no effect on alcohol dehydrogenase I or eight glycolytic enzymes. Tandem promoters from adhB expressed beta-galactosidase at higher levels than did either promoter alone in operon fusions. Addition of 50 microM zinc sulfate in minimal medium reduced the expression of adhB and of the operon fusions. Abundant but inactive alcohol dehydrogenase II was produced in iron-limited cells. This inactive enzyme did not form intracellular aggregates, and no morphological changes were apparent by transmission electron microscopy.
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PMID:Expression of Zymomonas mobilis adhB (encoding alcohol dehydrogenase II) and adhB-lacZ operon fusions in recombinant Z. mobilis. 250 92

A gene fusion approach to simplify protein immobilization and purification is described. A gene encoding the protein of interest is fused to a gene fragment encoding the affinity peptide Ala-His-Gly-His-Arg-Pro. The expressed fusion proteins can be purified using immobilized metal affinity chromatography. A vector, designed to ensure obligate head-to-tail polymerization of oligonucleotide linkers was constructed by in vitro mutagenesis. A linker encoding the affinity peptide, was synthesized and polymerized to two, four and eight copies. These linkers were fused to the 3' end of a structural gene encoding a two-domain protein A molecule, ZZ, and to the 5' end of a gene encoding beta-galactosidase. Fusion proteins, of both types, with zero or two copies of the linker showed little or no binding to immobilized Zn2+, while a relatively strong interaction could be observed for the fusions based on four or eight copies of the linker. Using a pH gradient, the ZZ fusions were found to be eluted from the resin at different pHs depending on the number of the affinity peptide. These results demonstrate that genetic engineering can be used to facilitate purification and immobilization of proteins to immobilized Zn2+ and that the multiplicity of the affinity peptide is an important factor determining the binding characteristics.
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PMID:Immobilization and affinity purification of recombinant proteins using histidine peptide fusions. 251 94

Site-directed mutagenesis was used to identify functional domains present within the human immunodeficiency virus (HIV) tat protein. Transient cotransfection experiments showed that derivatives of tat protein with amino acid substitutions either at the amino-terminal end or at cysteine residue 22, 37, 27, or 25 were no longer able to transactivate HIV long terminal repeat-directed gene expression. Incubation of Tat expressed in Escherichia coli with zinc demonstrated that both authentic Tat and cysteine mutation derivatives could form metal-protein complexes. The tat proteins that contained alterations within the cluster of positively charged amino acid residues retained their ability to transactivate gene expression, albeit at markedly reduced levels. Indirect immunofluorescence showed that the authentic tat protein and the amino-terminal and cysteine substitution mutants all localized in the nucleus, with accumulation being most evident in the nucleolus. In contrast, nuclear accumulation was greatly reduced with the basic-substitution mutations. Consistent with this result, a fusion protein that contained amino acids GRKKR, derived from the basic region, fused to the amino-terminal end of beta-galactosidase also accumulated within the nucleus. These results demonstrate that the 14-kilodalton tat protein contains at least three distinct functional domains affecting localization and transactivation.
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PMID:Structural and functional characterization of human immunodeficiency virus tat protein. 253 18

The yeast ADR1 protein contains two zinc finger domains that are essential for its role in transcriptional activation of alcohol dehydrogenase (ADH2). These domains are thought to function as DNA-binding structures. An ADR1-beta-galactosidase fusion protein made in Escherichia coli and containing the finger domains of ADR1 binds in vitro in a zinc-dependent manner to DNA fragments containing the two ADH2 upstream activation sequences. The strongest binding is to upstream activation sequence 1, a 22-base-pair palindrome.
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PMID:The yeast regulatory protein ADR1 binds in a zinc-dependent manner to the upstream activating sequence of ADH2. 314 94

1. Chicken brain arylsulphatase A was purified 2000-fold, with overall recovery 14%, by using ammonium sulphate fractionation, ethanol precipitation, Sephadex G-200 gel filtration and DEAE-Sephadex column chromatography. 2. The purified preparation was free from beta-glucuronidase, beta-galactosidase, acid phosphatase, inorganic pyrophosphatase and adenosine 3'-phosphate 5'-sulphatophosphate sulphohydrolase activities. 3. Polyacrylamide-gel electrophoresis indicated that the purified preparation was not homogeneous. 4. Chicken brain arylsulphatase was markedly inhibited by carbonyl reagents in the presence of traces of Cu(2+) in the system. Other metal ions such as Fe(2+) and Zn(2+), were inactive. 5. Ascorbic acid alone had no effect on enzyme activity but enhances the inhibition by Cu(2+). 6. Chicken brain arylsulphatase A resembled arylsulphatase A of other animal species in its kinetic properties such as K(m) value, anomalous time-activity relationship and the inhibitory effect of phosphate, sulphite and sulphate ions. However, its electrophoretic mobility, behaviour under zinc acetate fractionation and stimulation by Ag(+) were similar to arylsulphatase B of other animal species. Thus, this enzyme did not correspond to either arylsulphatase A or arylsulphatase B but properties of both. 7. The purified enzyme preparation can degrade cerebroside 3-sulphate.
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PMID:Purification and properties of arylsulphatase A from chicken brain. 507 33

Alkaline phosphate, catalase and beta-galactosidase activities of Vibrio et tor were decreased after acquisition of resistance towards rifampicin. Zn2+, Mn2+ and EDTA inhibited alkaline phosphatase which is most active with p-nitrophenylphosphate as substrate while Mg2+ was found to suppress alkaline phosphatase activity. Removal of EDTA however, restores the original activity. Rifampicin could not induce mutation of lactose nonfermenting Vibrio el for cells allowing them to grow on lactose as sole carbon source, z-galactosidase which is a constitutive enzyme in this case is repressed by glucose. This repression is overcome by cAMP.
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PMID:Studies on alkaline phosphatase, catalase and z-galactosidase in Vibrio el tor under normal and rifampicin resistant conditions. 618 76

A system is described for assessing the toxicity of freshly mixed restorative materials in vitro by measuring changes in the levels of beta-galactosidase and lactic dehydrogenase in both cultured cells and supernatants. The toxic effects of a zinc phosphate and silicate cement, a composite, and zinc oxide/eugenol were studied on two cell types, macrophages and fibroblasts, after 24 h exposure. Zinc oxide/eugenol, Silicap, and zinc phosphate were toxic to macrophages, in that order; Concise appeared to be nontoxic. Only zinc oxide/eugenol exerted significant effects on fibroblasts. Interposing dentine powder between the test cells and the material ameliorated the effects of all materials, possibly by the absorption of toxic components.
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PMID:A comparison of the in vitro cytotoxicity of four restorative materials assessed by changes in enzyme levels in two cell types. 621 26

Streptococcus mitis ATCC 903 aggregated when suspended in salt solutions containing the ions zinc, aluminium, lanthanum and cerium. This aggregation was very rapid as compared to spontaneous aggregation occurring in this strain. It was not inhibited by alkaline pH. Washed bacteria treated previously with zinc sulphate recovered and retained their ability to aggregate spontaneously at a slow rate. No such effect was observed with lanthanum-induced aggregation. The aggregates caused by lanthanum chloride were stable in sodium chloride up to 5 M concentrations. Magnesium sulphate dissociated these aggregates at 250 mM. Aggregation induced by zinc sulphate was less stable in these salts. The spontaneously aggregated cells were dissociated completely at 10 mM magnesium sulphate or 100 mM sodium chloride. Bacteria which had lost their ability to aggregate, owing to trypsin or beta-galactosidase treatment, were re-aggregated after addition of zinc, lanthanum or aluminium ions. Galactosamine inhibited the spontaneous aggregation and aggregation induced by zinc but not the aggregation induced by lanthanum or aluminium ions. In conclusion, the results provide a molecular model of induced and spontaneous aggregations where the two phenomena are qualitatively different.
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PMID:Induction of aggregation in Streptococcus mitis by certain ions. 644 Apr 11

Enzymatic activity was investigated in metal-binding proteins from rat epidermal cells. Tris-HCl buffer soluble and KSCN solubilized proteins were extracted stepwise from granular and cornified cells of 2-day old rat epidermis. Each extract was separately applied to a Cu2+ or Zn2+ chelate Sepharose 6B column and the proteins were eluted with buffers of different pHs and finally with EDTA solution. Metal chelate-binding proteins were found in both soluble and solubilized proteins but there was a larger amount in the latter. Affinity of the proteins to bind with Cu2+ chelate was greater than that with Zn2+ chelate. In Tris-HCl buffer extract, histidase activity was detected in Cu2+ chelate-binding proteins, but not in Zn2+ chelate-binding proteins. Acid phosphatase, cysteine proteinase, dipeptidase, cathepsin D, beta-galactosidase, gelatin hydrolase, and superoxide dismutase did not bind to metal chelates although these enzymes, except acid phosphatase, were inhibited by Cu2+, but not by Zn2+. In contrast, KSCN solubilized metal chelate-binding proteins showed plasminogen activator, acid phosphatase, and gelatin and casein hydrolases while histone hydrolase did not bind to either chelate column. Since metal-binding proteins in rat epidermal cells have been shown previously to be histidine- and cysteine-rich proteins concentrated in keratohyalin granules, interaction of metals and the structural proteins with certain enzymes may be involved in the regulation of epidermal cell functions.
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PMID:Enzymatic activity of metal-binding proteins in epidermal cells. 653 44

The properties and bile salt specificities of galactosylceramide and lactosylceramide beta-galactosidase activities (GC and LC-beta-galactosidases) of human leucocytes and fibroblasts were compared. A number of differences were observed. Under the standard assay conditions the former activity was more sensitive to Zn2+ and Triton-X100. Glycocholate and cholate were more active stimulators of the GC-beta-galactosidase than the more frequently used taurocholate which was the most effective stimulator of LC-beta-galactosidase activity. It is postulated that some of the apparent differences in the properties of GC- and LC-beta-galactosidase activities may be attributed to the different micellar properties of the lipid substrates. Experiments with fibroblasts from patients with Krabbe's disease confirmed an almost total absence of GC-beta-galactosidase whichever bile acid was employed. Residual LC-beta-galactosidase activity detected in these cells was much higher ranging from 13% of the lowest measured value when measured with taurocholate to approximately normal values with glycocholate. Fibroblasts obtained from patients with GM1-gangliosidosis displayed close to normal GC and LC-beta-galactosidase activity under our experimental conditions. The data suggest that diagnoses of Krabbe's disease should be performed with galactosylceramide rather than lactosylceramide as substrate.
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PMID:A comparison of the properties and bile salt specificities of galactosylceramide and lactosyl ceramide beta-galactosidase activities in human leucocytes and fibroblasts. 676 28


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