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

A 17-nucleotide-long synthetic DNA molecule constituting the minimal recognition sequence of the lactose operator has been cloned in E. coli using the vehicle pBR313 and a synthetic HindIII adaptor. The clones containing the lac-pBR313 hybrid DNA constitutively produced beta-galactosidase. The level of beta-galactosidase was high and comparable to that obtained in cells carrying a 21-nucleotide-long synthetic lac operator on pMB9 plasmid or cells carrying a natural lac operator on pOP203-1 plasmid.
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PMID:Cloned seventeen-nucleotide-long synthetic lactose operator is biologically active. 9 88

The activities of four lysosomal acid hydrolases, beta-galactosidase, alpha-mannosidase at pH 4.5 and 5.5, N-acetyl-beta-glucosaminidase, and acid phosphatase, have been measured in serum and cerebrospinal fluid from 179 patients with different neurological diseases and from 20 healthy controls. In patients with tumours, decreased activity of beta-galactosidase was found in both serum and cerebrospinal fluid, and in patients with multiple sclerosis and collagen diseases, decreased activities of beta-galactosidase and N-acetyl-beta-glucosaminidase were found in cerebrospinal fluid. The variations of enzyme activities were great between the individual patients even with these groups and analysis of lysosomal enzymes seems to have a very poor clinical value.
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PMID:Diagnostic value of determinations of lysosomal hydrolases in CSF of patients with neurological diseases. 9 53

In in vitro tests with lysosomes isolated from the liver and kidneys of castrated rats of both sexes the action of testosterone and beta-estradiol in concentrations of 3.76.10(-4)M on the activity of beta-glucosidase, beta-galactosidase and acid phosphatase was investigated. Testosterone is shown to reduce the total and free activity of the membrane-bound enzymes and to increase the release from the matrix lysosomes. Estradiol proved less active than is testosteron. The renal lysosomes in vitro are more sensitive to the action of sex hormones than are hepatic lysosomes. In the interaction of testosterone and estradiol with lysosomal membranes a sex specificity was revealed.
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PMID:[The effects of testosterone and estradiol on the activity of lysosomal enzymes in rat liver and kidneys]. 9 95

A strain of Escherichia coli in which the lacZ gene was fused to the bioA promoter was constructed. Colonies of this strain formed Lac(+) colonies on low-biotin agar (1.6 to 4.1 nM) and Lac(-) colonies on high-biotin agar (41 nM). This lac-bio fusion strain was used to study the question of whether cells growing on the biotin vitamers d-biotin-d-sulfoxide (BDS) and dethiobiotin (DTB) generate enough biotin to give maximal repression of beta-galactosidase synthesis. Repression by high concentrations (400 nM) of BDS was almost maximal (about 96%), whereas DTB repression reached a saturation level of about 80% with increasing DTB concentrations. The levels of repression obtained with both vitamers were sufficient to cause the colonies to appear Lac(-). When the lac-bio fusion was transduced into lines carrying mutations (bis) that prevent reduction of BDS to biotin, the transductants were not repressed by added BDS. Repression by BDS is unlikely to result from accumulation of extracellular biotin-related substances because (i) washed bis(+) cells were not detectably derepressed when transferred into medium containing BDS and (ii) washed bis cells were not detectably repressed when transferred into medium in which bis(+) cells had grown. Lactose agar plates containing high concentrations of DTB or BDS comprise an efficient selective medium for bioB or bis mutants and were used to isolate spontaneous mutations of these genes. This method should be adaptable to the selection of mutations in any biosynthetic pathway subject to end-product repression.
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PMID:Repression of biotin biosynthesis in Escherichia coli during growth on biotin vitamers. 9 77

We have developed an assay for the in vivo rate of beta-galactosidase synthesis in mouse tissues to assess the mechanism by which the Bgs and Bgt loci regulate activity levels of this enzyme. Genetically determined differences in liver and kidney beta-galactosidase content reflect equivalent differences in specific rates of enzyme synthesis. We conclude that Bgs and Bgt regulate beta-galactosidase activity by controlling the rate of synthesis of the beta-galactosidase molecule.
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PMID:Regulation of the rate of beta-galactosidase synthese by the Bgs and Bgt loci in the mouse. 9 89

The site of attachment to beta-galactosidase of the active site-directed inhibitor, beta-D-galactopyranosylmethyl p-nitrophenyl triazene, was determined. When the enzyme is completely inactivated, 1 mol of the galactopyranosylmethyl group is bound per mol of monomer with retention of the tetrameric structure. After reaction with the [14C]methyl reagent, labeled peptides were isolated and analyzed. The radioactive label was found to be covalently bound to methionine residue 500.
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PMID:Methionine 500, the site of covalent attachment of an active site-directed reagent of beta-galactosidase. 9 90

The amino acid sequence of 72 chymotryptic peptides isolated from 14C-, 3H-labeled carboxymethyl-beta-galactosidase has been determined. A variety of techniques were used in the isolation procedures including separation by solubility, size, and ion exchange and paper chromatography. These peptides contain approximatley 500 amino acids, range in size from 2 to 26 residues, and give overlaps with tryptic peptides of 16 to 55 residues. Peptides from this digest and those reported earlier from tryptic digests account together for the sequence of about 600 of the 1021 residues in the subunit.
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PMID:Amino acid sequence of beta-galactosidase. V. Isolation and sequences of chymotryptic peptides. 9 93

All of the 24 cyanogen bromide peptides of beta-galactosidase have been isolated in pure form. Of these 8 ranged in size from 2 to 5 residues and were purified by paper electrophoresis. The 16 large peptides, from 23 to 119 residues, were chromatographed at pH 5.0 on a carboxymethyl-cellulose column in 0.02 M ammonium acetate buffer containing 8 M urea. A number of peptides were obtained in pure from following Sephadex G-50 or G-75 gel filtration. Others were separated on sulfopropyl-Sephadex or diethyl-(2-hydroxylpropylaminoethyl)-Sephadex. There large peptides were obtained in over 50% yield and several others were obtained in more than 25% yield.
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PMID:Amino acid sequence of beta-galactosidase. VII. Isolation of the 24 cyanogen bromide peptides. 9 94

The amino acid sequence in the 8 cyanogen bromide peptides comprising the central segment of beta-galactosidase is presented. This portion of the molecule, about 27% of the protein, contains over 40% of the lysine and tyrosine residues and has a slight excess of basic amino acids.
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PMID:Amino acid sequence of beta-galactosidase. IX. Sequence of the central segment, CNBr peptides 10 to 17, residues 378 to 653. 9 96

The sequence of the COOH-terminal third (omega) of beta-galactosidase is presented. The size of the 7 cyanogen bromide peptides of this segment is larger on the average, about 52 amino acid residues as compared to an average size of 42 for cyanogen bromide peptides in the whole molecule. Tyrosine, phenylalanine, and valine are low in this segment whereas alanine and lysine are high. This region has a slight excess of basic groups.
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PMID:Amino acid sequence of beta-galactosidase. X. Sequence of the COOH-terminal segment, CNBr peptides 18 to 24, residues 654 to 1021. 9 97


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