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)

NADPH-cytochrome P-450 reductase was purified from hepatic microsomes of phenobarbital and hydrocortisone-treated rats by detergent solubilization and column chromatography. This membrane protein contains 31 mol per cent hydrophobic amino acid residues, 6 half-cystine residues, and a single tryptophan residue as determined by amino acid analysis after mineral or organic acid hydrolysis. The free mobility of cytochrome P-450 reductase in sodium dodecyl sulfate was identical to that of several soluble proteins used as standards (i.e. ovalbumin, bovin serum albumin, erythrocuprein, beta-galactosidase). Molecular weight estimates from sedimentation equilibrium studies in the presence of guanidine hydrochloride (76,500) are consistent with those determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate at various per cent gel concentrations (79,000 to 80,000). Computer analysis of circular dichroism spectra of cytochrome P-450 reductase in the far ultraviolet region indicated the presence of 34 per cent alpha helical and 16 per cent beta structure. The amount of random structure was calculated to be 50 per cent.
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PMID:NADPH-cytochrome P-450 reductase. Circular dichroism and physical studies. 1 69

The effect of structural modification on the enzyme-binding capacity of collagen has been studied using beta-galactosidase (E. coli K12) immobilized to collagen membrane by the impregnation procedure. The apparent steady-state activities of the resultant collagen-enzyme complexes were determined as a means of evaluating the enzyme-binding capacity of the modified collagen. In addition, the amount of enzymic protein bound to the collagen support was determined by the tryptophan content of the complex. The tertiary structure of the collage matrix was modified by cross-linking with the difunctional reagent, glutaraldehyde, and by aging in the dry state. Such structural modifications were found to markedly reduce the enzyme (beta-galactosidase) binding capacity of collagen films. The enzyme-binding capacity of the crosslinked collagen membrane was completely restored by proteolytic enzyme treatment of the aged film but only partly so for the glutaraldehyde treated films. Proteolytic enzymes used to treat a dispersion of collagen microfibrils prior to casting into a membrane also resulted in an increase in enzyme-binding. The effect of structural modification of collagen on enzyme-binding and the locus of enzyme attachment are discussed.
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PMID:Chemical modificiation of collagen and the effects on enzyme-binding: mechanistic considerations. 41 51

To study the mechanism by which bacteriophage T4 inhibits the synthesis of inducible host enzymes we measured the formation of beta-galactosidase from preformed lac mRNA. Beta-Galactosidase was induced with isopropyl-beta-D-thiogalactopyranoside in the presence of 7-azatryptophan, a tryptophan analogue that is incorporated into proteins and renders the beta-galactosidase formed inactive. The accumulated las mRNA was measured by capacity to form active beta-galactosidase after a chase of the analogue with excess tryptophan. After T4 infection the ability to form beta-galactosidase from the preformed lac mRNA was rapidly lost even when T4 infection took place in the presence of rifampin. This restriction was dependent on the multiplicity of infection. At a multiplicity of infection of 8.6, 90% of the ability to express preformed lac mRNA was lost within 30 s. The kinetics of cessation of beta-galactosidase synthesis after T4 infection indicate that infection blocks initiation of lac mRNA translation.
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PMID:Bacteriophage T4-induced shut-off of host-specific translation. 76 17

A tryptophan-requiring strain of Escherichia coli can go through two doublings of optical density after L-tryptophan is replaced in the medium by 4-fluorotryptophan, during which the fluoro analog displaces approximately 75% of the L-tryptophan in cell protein. One doubling occurs in the presence of 5- or 6-fluorotryptophan, with 50-60% replacement of L-tryptophan by analog. When beta-galactosidase is induced at the time of addition of analog, it reaches 60% of the control specific activity in the presence of 4-fluorotryptophan, 10% of normal in the presence of 5- or 6-fluorotryptophan. Lactose permease activity is 35% of the control in the presence of 4- and 6-fluorotryptophan, less than 10% in the presence of 5-fluorotryptophan. D-Lactate dehydrogenase shows a specific activity twice that of the control in the presence of 4-fluorotryptophan, one-half with 5- or 6-fluorotryptophan. Thus fluorotryptophan can be incorporated into proteins and affect their activities, although the nature and magnitude of the effect cannot be predicted for any given enzyme. Such substituted proteins should be useful for the study of protein structure and function by 19F nuclear magnetic resonance and other techniques.
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PMID:Incorporation of fluorotryptophans into proteins of escherichia coli. 109 37

The Caenorhabditis elegans protein, CeMyoD, is related to the vertebrate myogenic regulatory factors MyoD, myogenin, MRF-4 and Myf-5. Like its vertebrate counterparts, CeMyoD accumulates in the nucleus of striated muscle cells prior to the onset of terminal differentiation. CeMyoD also shares functional similarities with the vertebrate myogenic regulatory factors. Viral LTR driven expression of CeMyoD in mouse 10T1/2 cells can convert this cell line into myoblasts as well as efficiently trans-activate mouse muscle-specific promoters. Furthermore, mouse MyoD expression can activate a CeMyoD-beta-galactosidase reporter construct in a 10T1/2 co-transfection assay.
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PMID:Functional conservation of nematode and vertebrate myogenic regulatory factors. 133 34

Partitioning of beta-galactosidase in aqueous two-phase systems of poly(ethylene glycol) and potassium phosphate is reviewed. The affinity of Escherichia coli beta-galactosidase for the PEG-rich phase dominates also in beta-galactosidase fusion proteins and the concept of using beta-galactosidase as an affinity handle for extraction of other proteins, after fusion, is discussed. A hypothesis is presented, assuming that tryptophan residues at the surface of beta-galactosidase is responsible for its partitioning to the PEG rich phase, and the concept of poly-tryptophan handles fused to the target protein for extraction is introduced.
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PMID:Combined use of extraction and genetic engineering for protein purification: recovery of beta-galactosidase fused proteins. 136 76

We have used a full-length clone encoding rabbit tryptophan hydroxylase (TRH) to isolate the Drosophila homologue (DTPH). Southern analysis of Drosophila genomic DNA reveals a pattern indicative of a single gene. The single transcript is expressed in adult head and body mRNA but is also detected in mRNA from early embryos. The embryonic transcript is ubiquitously expressed and appears to concentrate in yolk granules. In situ hybridization of TRH-homologous antisense RNA probe to sectioned tissue from third instar larvae demonstrated the presence of this transcript in fat body and cuticular tissue. Developmental immunoblot analysis using antibodies raised against a beta-galactosidase-Drosophila fusion protein revealed a 45-kDa embryonic protein also detected in female abdomens and a 50-kDa protein found in larval and adult stages. Immunocytochemical analysis of the Drosophila protein in the larval central nervous system showed that it appeared to be present in both serotonin- and catecholamine-containing neurons. A nonfusion protein generated in Escherichia coli hydroxylates both tryptophan and phenylalanine. We propose that there are only two aromatic amino acid hydroxylase genes in Drosophila: one encoding tyrosine hydroxylase, DTH, and DTPH, a gene encoding both tryptophan and phenylalanine hydroxylase activities.
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PMID:A single locus encodes both phenylalanine hydroxylase and tryptophan hydroxylase activities in Drosophila. 137 Dec 86

As an approach to gene therapy for the respiratory manifestations of cystic fibrosis (CF), in vivo plasmid-mediated direct transfer of the normal CF transmembrane conductance regulator (CFTR) gene to the airway epithelium was investigated in mice. To evaluate the feasibility of this strategy, pRSVL, a plasmid composed of a firefly luciferase gene driven by the Rous sarcoma virus long terminal repeat (RSV-LTR), along with cationic liposomes was instilled into the trachea of C57BI/6NCR mice. With administration of 200-400 micrograms plasmid DNA, luciferase expression could be detected in the mouse lung homogenates for at least 4 wk. With this background, a CFTR expression plasmid vector (pRSVCFTR) constructed by replacing the luciferase cDNA from pRSVL with the normal human CFTR cDNA was evaluated in vivo in mice. Intratracheal instillation of pRSVCFTR with cationic liposomes followed by analysis of mouse lung RNA by polymerase chain reaction amplification (after conversion of mRNA to cDNA) using a RSV-LTR specific sense primer and a human CFTR-specific antisense primer demonstrated human CFTR mRNA transcripts from one day to 4 wk after instillation. Further, in vivo evaluation of beta-galactosidase activity after intratracheal administration of an E. coli lacZ gene expression plasmid vector directed by the cytomegalovirus promoter (pCMV beta) demonstrated that the airway epithelium was the major target of transfer and expression of the exogenous gene. These observations demonstrate successful plasmid-mediated gene transfer to the airway epithelium in vivo. This strategy may be feasible as a form of gene therapy to prevent the pulmonary manifestations of CF.
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PMID:Expression of the human cystic fibrosis transmembrane conductance regulator gene in the mouse lung after in vivo intratracheal plasmid-mediated gene transfer. 137 20

The levels of the tryptophan-sensitive isoenzyme of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase of Escherichia coli, encoded by the aroH gene, were elevated in tyrR and/or trpR mutants. The effect of tyrR and trpR lesions on aroH expression was confirmed by using a lacZ reporter system. The mutational elimination of either repressor led to a threefold increase in beta-galactosidase.
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PMID:The tyrosine repressor negatively regulates aroH expression in Escherichia coli. 167 35

An active preparation of human phospholipase A2 (PLA2) was made after expression as an insoluble fusion protein in Escherichia coli. The new key elements required for PLA2 isolation were the maintenance of the fusion protein in solution after the initial solubilization and the use of a tryptophan cleavage procedure for regeneration of native PLA2 from the fusion protein. The fusion protein was composed of a beta-galactosidase leader peptide incorporating six consecutive threonine residues to aid in insoluble inclusion body formation, followed by a tryptophan adjacent to the N-terminus of PLA2. The fusion protein was purified from cell lysates, and the leader peptide was cleaved on the C-terminal side of the tryptophan residue with N-chlorosuccinimide. The released PLA2 was refolded and renatured to produce an enzyme with activity comparable to that of other phospholipases A2.
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PMID:A strategy for obtaining active mammalian enzyme from a fusion protein expressed in bacteria using phospholipase A2 as a model. 182 81


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