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)

A gene coding for a Bowman-Birk-type proteinase inhibitor was synthesized chemically, cloned and expressed in Escherichia coli as a fusion protein with a beta-galactosidase fragment. The corresponding mutant inhibitor, carrying a P1 = Arg16 instead of Lys and an Ile27 instead of Met was obtained after cyanogen bromide cleavage, refolding and affinity chromatography on trypsin-Sepharose. Dissociation constants of complexes with trypsin of this mutant and wild-type Bowman-Birk inhibitor are identical within experimental error. This is explained by differential patterns of hydrogen bonds between side-chains of Arg or Lys in proteinase inhibitors and the primary specificity pocket of trypsin.
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PMID:Chemical synthesis, molecular cloning and expression of gene coding for a Bowman-Birk-type proteinase inhibitor. 329 96

Glutamic acid decarboxylase (GAD;E.C. 4.1.1.15) catalyzes the production of GABA, the major inhibitory neurotransmitter in the mammalian brain. We recently isolated a lambda gt-11 recombinant, lambda-GAD, that contains the cDNA for GAD from feline brain (Kaufman et al., 1986). Interestingly, the beta-galactosidase-GAD fusion protein encoded by lambda GAD is enzymatically active, catalyzing the conversion of glutamate to CO2 and GABA. Here we report the nucleotide sequence of feline GAD cDNA. It consists of 2265 bases, with a continuous open reading frame of 625 codons. The derived sequence contains the sequence Asn-Pro-His-Lys, which is identical to sequence at the pyridoxal phosphate-binding site of porcine DOPA decarboxylase (Bossa et al., 1977). The first ATG sequence in the open reading frame begins at nucleotide residue 118. The 585 codons 3' to this putative initiation site predict an amino acid composition, N-terminal residue, and molecular size consistent with published characterizations of GAD.
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PMID:Glutamic acid decarboxylase cDNA: nucleotide sequence encoding an enzymatically active fusion protein. 345 23

The Analytab system of 20 biochemical tests for identification of Enterobacteriaceae was evaluated in parallel with conventional tests on 128 Enterobacteriaceae, 5 Aeromonas, and 1 Yersinia enterocolitica. The results of tests for H(2)S and indole production, citrate utilization, lysine and ornithine decarboxylase, arginine dihydrolase, nitrate reduction, beta-galactosidase, and fermentation of arabinose, rhamnose, mannitol, and glucose showed almost complete agreement between the two systems. Eighty-eight per cent of Enterobacteriaceae were correctly speciated with the Analytab system; on repeat testing with heavier inocula of organisms failing to ferment glucose initially, the proportion of Enterobacteriaceae correctly speciated became 93%.
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PMID:Evaluation of accuracy of multitest micromethod system for identification of Enterobacteriaceae. 494 Aug 67

Extracts of Acanthamoeba castellanii (Neff) contain alpha- and beta-glucosidase, beta-galactosidase, beta-N-acetylglucosaminidase, amylase, and peptidase. All of these activities are optimal between pH 3 and 4. These extracts also were found to clarify suspensions of cell walls from nine different gram-positive bacteria, including Micrococcus lysodeikticus. The pH optimum for the lytic activity was between 3 and 4. The extent of lysis of the various cell walls did not correlate with the release of free amino groups and of free N-acetylated sugars from the walls during digestion with these extracts. Suspensions of cell walls of Escherichia coli (a gram-negative bacterium), Cordiceps militaris (a fungus), and Acanthamoeba cysts, as well as of colloidal chitin, were not clarified by incubation with these extracts, although reducing sugars were released from each of these materials. Exhaustive digestion of M. lysodeikticus walls by lysozyme released no free N-acetylglucosamine. The products of exhaustive digestion of this cell wall with Acanthamoeba extracts were free N-acetylglucosamine, free N-acetylmuramic acid, glycine, alanine, glutamic acid, lysine, and N-acetylmuramic acid peptide fragments. These results suggest that the amoeba extracts contain endo- and exo-hexosaminidases, in addition to beta-hexosaminidase and peptide hydrolases.
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PMID:Effect of lytic enzymes of Acanthamoeba castellanii on bacterial cell walls. 578 74

The Escherichia coli dapB gene encodes dihydrodipicolinate reductase. This enzyme is part of the diaminopimelate-lysine pathway, and its synthesis is repressed by lysine. The dapB gene was cloned into pBR322 from a transducing lambda bacteriophage, its complete nucleotide sequence established, and the transcriptional start localized. The DNA sequence predicts that the dapB gene codes for a 273-amino acid polypeptide, Mr 28,798. No attenuation-type sequence can be found between the mRNA start and the coding sequence. The dapB promoter signals appear to be weak as compared to RNA polymerase consensus sequences. Nevertheless an efficient in vivo synthesis of beta-galactosidase was obtained when the lac operon was inserted in vitro in the dapB gene, downstream of the dapB regulatory signals. Further studies were performed on an in-frame gene fusion constructed in vitro between the dapB and the lacZ genes. They indicated that repression by lysine is exerted on a DNA region restricted to a 153-base pair fragment with only 102 nontranscribed nucleotides. Finally, dapB gene expression showed a gene dosage effect which suggests that it is not controlled by an element present in limiting amounts in the cell.
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PMID:Nucleotide sequence and expression of the Escherichia coli dapB gene. 609 78

A short sequence of amino acids including Lys-128 is required for the normal nuclear accumulation of wild-type and deleted forms of SV40 large T antigen. A cytoplasmic large T mutant that lacks sequences from around Lys-128 localizes to the nucleus if the missing sequence is attached to its amino terminus. The implication that the sequence element around Lys-128 acts as an autonomous signal capable of specifying nuclear location was tested directly by transferring it to the amino termini of beta-galactosidase and of pyruvate kinase, normally a cytoplasmic protein. Sequences that included the putative signal induced each of the fusion proteins to accumulate completely in the nucleus but had no discernible effect when Lys-128 was replaced by Thr. By reducing the size of the transposed sequence we conclude that Pro-Lys-Lys-Lys-Arg-Lys-Val can act as a nuclear location signal. The sequence may represent a prototype of similar sequences in other nuclear proteins.
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PMID:A short amino acid sequence able to specify nuclear location. 609 7

Mutants containing fusions of the lac gene to the lysC gene were isolated. In these, the expression of beta-galactosidase was regulated by lysine (and arginine), as previously described for aspartokinase III.
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PMID:Regulation of aspartokinase III synthesis in Escherichia coli: isolation of mutants containing lysC-lac fusions. 624 91

The ompB region on the Escherichia coli chromosome codes for two genes, ompR and envZ, which are required for the osmolarity sensitive biosynthetic regulation of the outer membrane matrix proteins (porins), OmpF and ompC. A part of the ompB region containing the ompR gene has been cloned (Wurtzel, E. T., Movva, N. R., Ross, F. L., and Inouye, M. (1981) J. Mol. Appl. Genet. 1, 61-69). We have determined the DNA sequence, including the promoter and structural regions encompassed in a 1.3-kilobase pair Ava I-Eco RI subfragment. This fragment codes for the entire ompR gene as well as the 5' end of the envZ gene. The ompR gene codes for a protein of 32,489 daltons, consisting of 284 amino acid residues. This was confirmed by identifying the gene product by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and determining a partial amino acid sequence of the NH2-terminal region of the gene product. A sequence of 57 amino acid residues located in the COOH-terminal region of the protein is extremely basic. It contains 10 arginine plus lysine residues in contrast to 1 glutamic acid residue in this region. In vitro transcription of the DNA from this region indicates that ampR and envZ are co-transcribed as a polycistronic mRNA from a promoter located 5' to the ompR gene. Translation of the am pR gene terminates at two tandem TAS codons and translation of the envZ gene initiates 29 nucleotides downstream. Cloning of the promoter region of ompB at a site 5' to the structural portion of the beta-galactosidase gene indicates that transcription of ompB is under positive control by cAMP.
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PMID:Osmoregulation of gene expression. I. DNA sequence of the ompR gene of the ompB operon of Escherichia coli and characterization of its gene product. 629 99

A fusion between the genes for bacteriorhodopsin and beta-galactosidase was constructed on a multicopy plasmid, pXB/Gal 101. The fusion gene, containing the bacteriorhodopsin gene fused upstream from the beta-galactosidase gene, was under the control of tandem lipoprotein and lac gene promoters. When expressed in Escherichia coli the fusion protein retained beta-galactosidase activity. Mutations in the fusion gene were produced by passage of pXB/Gal 101 through the E. coli mutator strain mut D5. Amber mutations were then selected by examining the loss of the lac+ phenotype imparted by the fusion protein to lac- E. coli cells. Amber mutations occurring within the bacteriorhodopsin gene were localized by replacing the beta-galactosidase region of each mutant plasmid with a beta-galactosidase region which was known to be unmutated. Precise localization of the mutations was achieved first by sizing the prematurely terminated peptides produced by the mutant plasmids in in vitro coupled transcription-translation reactions, and secondly by DNA sequence analysis. Six amber mutants in the gene for bacteriorhodopsin were characterized in this way. One of these was a transversion mutation at a lysine codon; the other five were all transition mutations at tryptophan codons, codons 10, 12, 80, 86, and 137 of the bacteriorhodopsin sequence.
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PMID:Introduction and characterization of amber mutations in the bacteriorhodopsin gene. 630 86

A new cytoplasmic endoprotease, named protease So, was purified to homogeneity from Escherichia coli by conventional procedures with casein as the substrate. Its molecular weight was 140,000 when determined by gel filtration on Sephadex G-200 and 77,000 when estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Thus, it appears to be composed of two identical subunits. Protease So had an isoelectric point of 6.4 and a K(m) of 1.4 muM for casein. In addition to casein, it hydrolyzed globin, glucagon, and denatured bovine serum albumin to acid-soluble peptides but did not degrade insulin, native bovine serum albumin, or the "auto alpha" fragment of beta-galactosidase. A variety of commonly used peptide substrates for endoproteases were not hydrolyzed by protease So. It had a broad pH optimum of 6.5 to 8.0. This enzyme is a serine protease, since it was inhibited by diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride. Although it was not inhibited by chelating agents, divalent cations (e.g., Mg(2+)) stabilized its activity. Protease So was sensitive to inhibition by N-tosyl-l-phenylalanine chloromethyl ketone but not by N-tosyl-l-lysine chloromethyl ketone. Neither ATP nor 5'-diphosphate-guanosine-3'-diphosphate affected the rate of casein hydrolysis. Protease So was distinct from the other soluble endoproteases in E. coli (including proteases Do, Re, Mi, Fa, La, Ci, and Pi) in its physical and chemical properties and also differed from the membrane-associated proteases, protease IV and V, and from two amino acid esterases, originally named protease I and II. The physiological function of protease So is presently unknown.
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PMID:Purification and characterization of protease So, a cytoplasmic serine protease in Escherichia coli. 633 74


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