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)

Simulation and optimization of continuous affinity recycle extraction (CARE), a protein purification unit operation based on protein adsorption to solid phase adsorbents, is described in this paper. Rather than packing conventional adsorbent particles in a fixed bed (column), solid/liquid contact is carried out in well-mixed reactors. Continuous operation is achieved by recirculation of the adsorbent particles between two or more contactors. The feasibility of this purification scheme was established with the recovery and isolation of the enzyme beta-galactosidase from E.coli, using the affinity support PABTG/Agarose. A mathematical model describing system performance was developed. The mathematical model was used to optimize several facets of the system design and operation. The base two-stage contractor design was modified by the addition of an intermediate wash stage as well as the incorporation of multiple adsorption stages. These design modifications serve to increase purification, concentration and recovery while utilizing the same amount of adsorbent. The methodology for defining and optimizing objective functions was developed and experimentally validated. Finally, optimum system start-up protocols, minimizing the time required to reach steady-state operation, were developed and experimentally validated. The impact of early introduction of adsorptive purification in a downstream processing sequence, with CARE, was evaluated and is described. Through the early introduction of a highly specific adsorptive step, significant purification is achieved simultaneously with clarification and concentration. In addition, purification performance in CARE was contrasted with that achievable in conventional column chromatography.
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PMID:Optimization and simulation of continuous affinity-recycle extraction (care). 136 63

Polypurine/polypyrimidine sequences have been shown to adopt intramolecular triple helix structures under torsional stress and/or at low pH. Such sequences have been observed within the the regulatory as well as the coding regions of several genes and the involvement of triple helical structure adopted by these sequences in transcriptional control has been speculated. Taking advantage of codon degeneracy we have engineered a 38 bp long intramolecular triple helix potential polypurine/polypyrimidine sequence motif between the 37th and 50th codons of beta-galactosidase gene in the plasmid pBluescriptIISK+ to investigate whether in vivo E.coli RNA polymerase would transcribe sequence motifs adopting triple helix structure, when present within the coding region of the gene. E.coli JM109 cells transformed with this construct pSBT1, exhibited 80% inhibition of beta-galactosidase expression compared to another construct pSBmT12 made using less preferred codons for identical amino acid sequence, but lacking the polypurine/polypyrimidine sequence motif. Truncated beta-galactosidase transcripts were observed for pSBT1 but not for pSBmT12. Here we report that a putative triple helix potential sequence within a gene can down regulate its expression by partially blocking the transcription elongation in vivo.
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PMID:Intramolecular triplex potential sequence within a gene down regulates its expression in vivo. 145 35

Active 3C protease of poliovirus 1(M) was obtained when cloning and expressing fragment HindII-HindIII (bases from 5240 to 6056) of cDNA in vector pTTQ8 in E.coli cells. As shown, fragment 3D of polymerase covalently bound to 3C does not deprive the enzyme of its specific proteolytic activity. The absence of 26 N-terminal amino acids in 3C entails its inactivation. The recombinant 3C protease cleaved peptide bond Gln-Gly not only in virus polyprotein, but also in molecules of beta-galactosidase and bovine catalase.
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PMID:Recombinant poliovirus 3C protease. The enzyme application to protein specific fragmentation. 164 25

Tc1 is a transposon present in several copies in the genome of all natural isolates of the nematode C.elegans; it is actively transposing in many strains. In those strains Tc1 insertion is the main cause of spontaneous mutations. The transposon contains one large ORF that we call TcA; we assume that the TcA protein is the transposase of Tc1. We expressed TcA in E.coli, purified the protein and showed that it has a strong affinity for DNA (both single stranded and double stranded). A fusion protein of beta-galactosidase and TcA also exhibits DNA binding; deletion derivatives of this fusion protein were tested for DNA binding. A deletion of 39 amino acids at the N-terminal region of TcA abolishes the DNA binding, whereas a deletion of 108 C-terminal amino acids does not affect DNA binding. This shows that the DNA binding domain of TcA is near the N-terminal region. The DNA binding capacity of TcA supports the assumption that TcA is a transposase of Tc1.
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PMID:TcA, the putative transposase of the C. elegans Tc1 transposon, has an N-terminal DNA binding domain. 215 34

The generally accepted hypothesis that exons code for fundamental polypeptide structures was tested with a fusion protein consisting of almost the entire polypeptide coded by exon 2 of chicken lysozyme fused to the N-terminus of beta-galactosidase of E.coli. Exon 2 encodes residues 28-81 of lysozyme. It thus contains Glu 35 and Asp 52, which are essential for hydrolysis of glycosidic bonds. The exon 2-beta-galactosidase fusion protein hydrolysed the substrate 4-methylumbelliferyl-N,N',N''-triacetyl-chitotrioside with a reaction rate about 1/40,000 of that of native lysozyme. The low hydrolysis rate of exon 2-peptide is partially caused by its low affinity to its substrate.
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PMID:50 residues coded by exon 2 of chicken lysozyme carry residual catalytic activity. 264 4

A synthetic gene coding for the bacteriocidal protein caltrin/seminalplasmin was constructed and expressed in Escherichia coli as a fusion with beta-galactosidase. The gene was designed with a recognition site for the plasma protease, Factor Xa, coded for immediately prior to the N-terminus of caltrin. The beta-galactosidase-caltrin fusion protein was cleaved with Factor Xa to give caltrin, which was identified by its size on SDS-PAGE, its ability to react with an antiserum raised to the N-terminal nonapeptide of caltrin and its N-terminal amino acid sequence. After partial purification, synthetic caltrin was found to be active in an assay involving inhibition of growth of E.coli.
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PMID:Cloning and expression in E. coli of a synthetic gene for the bacteriocidal protein caltrin/seminalplasmin. 333 97

The expression of the diphtheria tox228 gene encoding the nontoxic, serologically related CRM228 mutant diphtheria toxin has been analyzed in Corynebacterium diphtheriae and Escherichia coli. The diphtheria toxin promoter has been used to direct the expression of beta-galactosidase in E.coli, and the efficiency of promotion has been compared to that obtained with the lac promoter. Expression in C.diphtheriae is known to be dependent on the absence of iron, and we present for the first time direct evidence that this regulation occurs at the level of transcription. The 5' end of toxin mRNA maps at the same position in C.diphtheriae and E.coli, suggesting identical sequences to be recognized by C.diphtheriae and E.coli RNA polymerase. The diphtheria toxin promoter carries at position -34 a TTGATT sequence closely related to the E.coli -35 consensus sequence and in the -14 to -8 region a set of overlapping sequences with complete or partial homology to the E.coli -10 consensus sequence.
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PMID:Diphtheria toxin promoter function in Corynebacterium diphtheriae and Escherichia coli. 392 42

Rapid killing of Escherichia coli by intact or disrupted rabbit granulocytes or by granulocyte fractions was found to be accompanied by an equally rapid increase in permeability of the E.coli envelope. This increase in permeability was detected by determining entry of substances that normally do not cross E.coli's permeability barrier, namely actinomycin D and o-nitrophenyl-beta-D-galactopyranoside (ONPG), a substrate for cytoplasmic beta-galactosidase. Because E.coli continue to incorporate radioactively labeled precursors into bacterial RNA and protein for at least 1 h, despite rapid killing by granulocytes, entry of actinomycin D could be measured by its inhibitory effect on macromolecular synthesis. Entry was evident within minutes after exposure to granulocytes or granulocyte fractions and is independent of pH over a range of 6.5-9.0. The effect of disrupted granulocytes or partially purified fractions on susceptibility of E.coli to actinomycin D and entry of ONPG is dose dependent. That the entry of actinomycin D and ONPG was not caused by gross destruction of the envelope is indicated by two sets of observations: (a) net influx of (42)K was maintained for at least 15 min, even though efflux of potassium was immediately accelerated upon addition of bactericidal concentrations of granulocyte fractions; (b) beta-galactosidase did not leak out of E.coli under conditions that produce maximal inhibition by actinomycin D. Different species of gram-negative bacteria exhibited different susceptibilities to the bactericidal and permeability effects of granulocyte fractions. Thus, three strains of E.coli and one strain of Salmonella typhimurium were highly susceptible to both the bactericidal and the permeability enhancing effects of granulocyte fractions, whereas two strains of Serratia marcescens and one strain of Pseudomonas aeruginosa were resistant to both effects. Another strain of P. aeruginosa was rendered susceptible to actinomycin D without being killed and two strains of S. typhimurium remained insensitive to actinomycin D while being killed by granulocytes.
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PMID:Early and discrete changes in permeability of Escherichia coli and certain other gram-negative bacteria during killing by granulocytes. 460 82

Hepatitis B is a widespread viral disease. In the absence of cell cultures capable of propagating the virus (HBV) an efficient vaccine has been prepared from viral envelopes isolated from the plasma of chronic carriers. The major polypeptide of the envelope is one of molecular weight 25,000 which carries the surface antigen (HBsAg). Therefore, the biosynthesis of this polypeptide in Escherichia coli may offer an alternative procedure to produce HbsAg free from human proteins. Recently, the HBV genome has been cloned in E.coli. Determination of its primary structure allowed the localization of the gene (called gene S) coding for HBsAg and the synthesis of the core antigen in E.coli has been reported. We have constructed a derivative of bacteriophage lambda carrying a fusion between the beta-galactosidase gene (lacZ) and the HBsAg coding sequence (lambdalacHBs-1). Infection of E.coli with lambdalacHBs-1 leads to the biosynthesis of a polypeptide of molecular weitht 138,000 carrying antigenic determinants of HBV surface antigen.
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PMID:Biosynthesis of hepatitis B virus surface antigen in Escherichia coli. 615 92

An open reading frame upstream from nifHDK operon of Klebsiella pneumoniae had been described. The orientation of this open reading frame is opposite to that of nifHDK and sequence homology was found between the open reading frame promoter and the promoter of nifHDK operon. A recombinant plasmid carrying the promoter region of the open reading frame fused to the beta-galactosidase gene was constructed. Strains of E.coli were transformed with the plasmid containing this open reading frame promoter-lacZ fusion or co-transformed with it and a plasmid carrying the nifA gene. An appreciable activity of beta-galactosidase was found in strains which received both plasmids, indicating that the promoter of the open reading frame can be activated by the product of nifA gene. Thus, the open reading frame found between nifHDK operon and nifJ behaves just like other nif genes of K.pneumoniae in requiring the product of nifA as the positive effector for expression.
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PMID:An open reading frame upstream from the nifH gene of Klebsiella pneumoniae. 630 80


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