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  • 1
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 395 (1998), S. 27-28 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The decontamination of large areas that have been exposed to chemical weapons is a critical component of defence and anti-terrorist strategies around the world. Until now, nerve agents could be decontaminated only with bleach treatment and/or ex situ incineration, which had severe environmental ...
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 338 (1989), S. 172-174 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In E. coli, ATCase (EC 2.1.3.2, the first enzyme distinct to pyrimidine biosynthesis3) and OTCase (EC 2.1.3.3, enzyme in step six of arginine biosynthesis4) catalyse the condensation of the carbamoyl moiety of carbamoyl phosphate with aspartateand ornithine respectively. Although native ATCase from ...
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  • 4
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A 6.0-kilobase fragment was isolated from purified ADNA4, restricted with the endonuclease Pstl (Bethesda Research Laboratory)5, and cloned on to plasmid pBR322 (ref. 6). The recombinant plasmid pPB-h204 (plasmid-pyrimidine-B cistron-holoenzyme-strain 204) was transformed into E. coli WR38, which ...
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 352-358 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The broad-spectrum organophosphate hydrolase (OPH; EC 3.1.8.1) encoded by the organophosphate-degrading gene (opd) from Pseudomonas diminuta MG and Flavobacterium sp. ATCC 27551 possesses capabilities of both P-O bond hydrolysis (e.g. paraoxon) and P-F bond hydrolysis [e.g. sarin and diisopropylfluorophosphate (DFP)]. In the present study a 9.4-kb plasmid, pCL1, was used to transform the saprophytic fungus Gliocladium virens. pCL1 was derived from pJS294 by placing the fungal promoter (prom1) from Cochliobolus heterostrophus upstream and the trpC terminator from Aspergillus nidulans downstream of the opd gene. Southern analysis of restricted genomic DNA from various transformants indicated that integration occurred non-specifically at multiple sites. Western blot analysis of mycelial extracts from transformants confirmed the production of a processed form of the enzyme in the fungus. Maximal levels of OPH activity (rate of p-nitrophenol production from paraoxon) were observed after 168 h of culture and activity levels correlated with biomass production in mature vegetative growth.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 17 (1988), S. 189-194 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract A rapid, filter-lift assay was developed for the identification of bacteria capable of degrading organophosphorus pesticides. Filter pads impregnated with parathion were applied to the surface of plates containing potential parathion-degrading colonies. Positive colonies capable of converting parathion to 4-nitrophenol attain a visible yellow coloration after 30 min of exposure; however, the identification of selected individuals was difficult when large numbers of colonies were screened on a single plate. An enhancement of this screening method was achieved with the use of UV-photography, which allowed for the detection of a single mutant or cured colony among 500 parathion-degrading colonies per plate. In addition, it was possible to detect a single parathion-degrading colony among 10,000 non-degrading colonies per plate. The efficiency of the technique was validated with a parathion-degrading strain ofPseudomonas diminuta from which phenotypically negative isolates were selected, subjected to plasmid isolation, evaluated for detoxifying activity, and tested by a battery of microbiological criteria to confirm the parental strain phenotype. All non-productive colonies were identical to the parental strain except for the lack of detoxifying capability and the loss of a large plasmid found in the parental strain.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Biochemical genetics 15 (1977), S. 173-193 
    ISSN: 1573-4927
    Keywords: Serratia marcescens ; pyrimidine biosynthesis ; enzyme aggregation ; regulation ; bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Orotidine-5′-monophosphate pyrophosphorylase (OMPppase, E.C. 2.4.2.10) and orotidylate decarboxylase (OMPdecase, E.C. 4.1.1.23) were purified from Serratia marcescens HY. These enzymes required physical association for maximal catalytic activities and formed a fragile complex with dihydroorotase (DHOase, E.C. 3.5.2.3.). OMPppase reversibly lost 50% of its activity upon separation from DHOase. The kinetic characteristics of OMPppase were modified by this separation. In the presence of DHOase, the K ms for PRPP and orotate were stoichiometric: 2.3×10−6 m and 2.6×10−6 m, respectively. Following separation, the K ms were significantly different: 1.3 × 10−6 m for PRPP and 4.1×10−6 m for orotate. OMPppase and OMPdecase could be reversibly separated by acrylamide gel electrophoresis, but the separation was accompanied by a loss of catalytic efficiency for both enzymes. DHOase readily associated into multiple molecular forms and could not be purified. The DHOase-OMPppase-OMPdecase interactions demonstrate that a weakly aggregated, multifunctional enzyme complex participates in the biosynthesis of pyrimidine nucleotides in S. marcescens. This unique association of nonsequential biosynthetic enzymes may represent a larger complex which provides a channeling or regulatory unit.
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  • 8
    ISSN: 1573-4927
    Keywords: Serratia marcescens ; pyrimidine biosynthesis ; coordinate expression ; regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The coordinate expression of four sequential enzymes in the de novo pyrimidine pathway may result from the interaction of the various polypeptides of the pathway in Serratia marcescens rather than represent some unit of transcriptional regulation. These interactions were defined by examining the polypeptide association observed in extracts of parental and mutant strains in a series of pleiotropic pyrimidine auxotrophs. Extracts of pyrE auxotrophs [possessing dihydroorotate (DHOase) activity but no orotidine-5′-monophosphate pyrophosphorylase (OMPppase) activity] stimulate OMPppase activity in extracts of pyrC auxotrophs (possessing reduced OMPppase activity but no DHOase activity). Separation by molecular weight on Sephadex G200 has suggested an aggregation between the final two enzymes, OMPppase and OMPdecarboxylase (OMPdecase), and the earlier enzyme, DHOase. The reduction of OMPppase activity in pyrC auxotrophs (encoding either a defective polypeptide or reduced levels) is explained by the lack of adequate levels of DHOase for aggregate formation. Such polypeptide interactions appear to mimic the coordinate formation of polypeptides which are controlled as a unit of regulation. The measurable levels of enzymatic activity vary in a quantitatively identical manner, but the variation does not result directly from the regulation of polypeptide formation.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 54 (1997), S. 105-114 
    ISSN: 0006-3592
    Keywords: enzymes ; phosphotriesterase ; immobilization ; polyurethane foam ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Phosphotriesterase (EC 3.1.8.1) was immobilized within a polyurethane foam matrix during polymer synthesis using a prepolymer synthesis strategy. In addition to retaining greater than 50% of the enzyme specific activity, numerous benefits were incurred upon immobilization. Orders of magnitude increases in storage and thermal stability (net stabilization energy = 12.5 kJ/mol) were observed without the need for enzyme premodification. The immobilized enzyme system was protease resistant and seemed to display no adverse effects from immobilization, such as an alteration of enzyme function. The organic solvent, dimethyl sulfoxide, also exhibited a stabilizing effect on phosphotriesterase enzyme systems over a range of intermediate concentrations. We attribute these effects in part to direct interaction between the aprotic solvent and metal containing residues present at the enzyme's active site. Our data demonstrate that just 2.5 kg of immobilized enzyme may be sufficient to degrade 30,000 tons of nerve agent in just 1 year. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 105-114, 1997.
    Additional Material: 11 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 187 (1982), S. 391-400 
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The two polypeptide chains that comprise aspartate carbamoyltransferase in Escherichia coli are encoded by adjacent cistrons expressed in the order, promoter-leader-catalytic cistron-regulatory cistron (p-leader-pyrBI). These two cistrons and their single control region have been cloned as a 2,800 base pair (bp) fragment (The minimal coding requirement for the catalytic and regulatory polypeptides is about 1,350 bp plus control regions). The genes contained by this fragment are subject to normal repression controls and thus possess the intact control regions. 2. By deleting an internal fragment with specific restriction endonucleases, it was possible to construct shortened fragments which no longer produced the regulatory polypeptide. In these cases the expression of the catalytic cistron was normal and subject to repression upon growth in the presence of uracil. Since the pyrB cistron retained transcriptional control, the regulatory polypeptide was not required for expression or control of the catalytic cistron. As expected, the catalytic trimer (Mr=100,000 daltons) from these deletion mutants had no effector response nor did it exhibit homotropic kinetics for aspartate. The enzyme was identical to the c3 trimer purified from the native holoenzyme by neohydrin dissociation. 3. Insertion of Mu d1(lac Apr) into the structural region of pyrB had a negative effect on the expression of pyrI. This supports the idea that the catalytic and regulatory polypeptide chains of aspartate carbamoyl-transferase are encoded by a single bioistronic operon. Detailed restriction analysis of the cloned pyrBI region has produced a genetic map of restriction sites which is colinear with the published amino acid sequences of the two polypeptides. These maps indicate that the 3′-terminus of the catalytic cistron is adjacent to the 5′-terminus of the regulatory cistron and separated by 10–20 bp. 4. DNA sequence analysis of the 5′-proximal regions of pyrBI revealed that an extensive leader sequence separated the promoter and first structural gene pyrB. This leader of approximately 150 bp contains an attenuator sequence and the translational signals required for the production of a leader polypeptide of 43 amino acids. In this paper we describe the structural organization of pyrBI, and provide a detailed analysis of its regulatory region including its DNA sequence.
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