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  • Electronic Resource  (30)
  • Polymer and Materials Science  (26)
  • Corynebacterium glutamicum  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Purification and properties of oxaloacetate decarboxylase fromCorynebacterium glutamicum (1995)
    Springer
    Antonie van Leeuwenhoek 67 (1995), S. 221-227 
    Details
    ISSN: 1572-9699
    Keywords: lysine biosynthesis ; aspartate-derived amino acids ; oxaloacetate decarboxylase ; pyruvate kinase ; Corynebacterium glutamicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oxaloacetate (OAA) decarboxylase (E.C. 4.1.1.3) was isolated fromCorynebacterium glutamicum. In five steps the enzyme was purified 300-fold to apparent homogeneity. The molecular mass estimated by gel filtration was 118 ± 6 kDa. SDS-PAGE showed a single subunit of 31.7 KDa, indicating an α4 subunit structure for the native enzyme. The enzyme catalyzed the decarboxylation of OAA to pyruvate and CO2, but no other α-ketoacids were used as substrate. The cation Mn2+ was required for full activity, but could be substituted by Mg2+, Co2+, Ni2+ and Ca2+. Monovalent ions like Na+, K+ or NH 4 + were not required for activity. The enzyme was inhibited by Cu2+, Zn2+, ADP, coenzyme A and succinate. Avidin did not inhibit the enzyme activity, indicating that biotin is not involved in decarboxylation of OAA. Analysis of the kinetic properties revealed a K m for OAA of 2.1 mM and a K m of 1.2 mM for Mn2+. The V max was 158 µmol of OAA converted per min per mg of protein, which corresponds to an apparent k cat of 311 s−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00871217
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  • 2
    Electronic Resource
    Electronic Resource
    Nucleotide sequence of the lysA gene of Corynebacterium glutamicum and possible mechanisms for modulation of its expression (1988)
    Springer
    Molecular genetics and genomics 212 (1988), S. 112-119 
    Details
    ISSN: 1617-4623
    Keywords: Corynebacterium glutamicum ; lysA promoter(s) ; Weak expression ; Full expression ; Bacterial evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sequence analysis localized the lysA gene of Corynebacterium glutamicum strain AS019 within a 1.35 kb open reading frame, potentially encoding a 445 amino acid product. Immediately downstream from this gene we found a potential ρ-independent transcription terminator, while the 5′ flanking region (300 bp) harbors unusual topological and structural features, located in the vicinity of a potential ribosome binding site. Within this upstream region, enzymatic and genetic analyses indicated the occurrence of a promoter responsible for significant, although weak, expression of the encoded enzymatic activity. The same significant expression level was observed with a plasmid harboring an additional 0.5 kb of genomic information upstream from lysA, while its full expression apparently requires 2 kb of additional genomic information located immediately upstream from the cloned gene. The upstream sequence requirement apparently associated with the full expression of the lysA gene of C. glutamicum shows some similarity with the Escherichia coli system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00322452
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  • 3
    Electronic Resource
    Electronic Resource
    General organization of the genes specifically involved in the diaminopimelate-lysine biosynthetic pathway of Corynebacterium glutamicum (1988)
    Springer
    Molecular genetics and genomics 212 (1988), S. 105-111 
    Details
    ISSN: 1617-4623
    Keywords: Corynebacterium glutamicum ; Diaminopimelate-lysine anabolic pathway ; Heterologous complementation ; Homologous expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We utilized diaminopimelate-lysine mutants of Escherichia coli K12 to clone the genes specifically involved in the Corynebacterium glutamicum diaminopimelate-lysine anabolic pathway. From a cosmid genomic bank of C. glutamicum strain AS019, we isolated cosmids pSM71, pSM61 and pSM531, that are respectively able to complement dapA/dapB, dapD, and lysA mutants of E. coli. DNA hybridization analysis indicates that these complementing genes are located on the chromosome of C. glutamicum in at least three separate transcription units. Subcloning of parental cosmids in dapA, dapD, and lysA mutants of E. coli localized these genes, respectively, within 1.4, 3.4, and 1.8 kb fragments, cloned in an E. coli/C. glutamicum shuttle vector. Enzymatic analysis in C. glutamicum identified the dapA-complementing gene as l-2,3-dihydrodipicolinate synthetase (dapA), and the lysA-complementing gene as meso-diaminopimelate decarboxylase (lysA). In contrast, complementation of E. coli dapD8, presumably lacking L-Δ1-tetrahydrodipicolinate synthetase (dapD), led us to clone a diaminopimelate-lysine anabolic gene of C. glutamicum which does not exist in E. coli: meso-diaminopimelate dehydrogenase. Although meso-diaminopimelate is crucial in lysine formation and in cell wall biosynthesis, expression of the genomic copies of the cloned genes, which encode activities involved at key branching points of the diaminopimelate-lysine pathway of C. glutamicum, appears constitutive with regard to the addition of diaminopimelate and/or lysine during cell growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00322451
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  • 4
    Electronic Resource
    Electronic Resource
    The phosphoenolpyruvate carboxylase gene of Corynebacterium glutamicum: Molecular cloning, nucleotide sequence, and expression (1989)
    Springer
    Molecular genetics and genomics 218 (1989), S. 330-339 
    Details
    ISSN: 1617-4623
    Keywords: Corynebacterium glutamicum ; Phosphoenolpyruvate carboxylase ; ppc gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ppc gene of Corynebacterium glutamicum encoding phosphoenolpyruvate (PEP) carboxylase was isolated by complementation of a ppc mutant of Escherichia coli using a cosmid gene bank of chromosomal c. glutamicum DNA. By subsequent subcloning into the plasmid pUC8 and deletion analysis, the ppc gene could be located on a 3.3 kb SalI fragment. This fragment was able to complement the E. coli ppc mutant and conferred PEP carboxylase activity to the mutant. The complete nucleotide sequence of the ppc gene including 5′ and 3′ flanking regions has been determined and the primary structure of PEP carboxylase was deduced. The sequence predicts a 919 residue protein product (molecular weight of 103154) which shows 34% similarity with the respective E. coli enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331286
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  • 5
    Electronic Resource
    Electronic Resource
    The controlled flocculation of submicron emulsion particles. I. A three-step synthetic route to supermicron polymer particles (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 3061-3069 
    Details
    ISSN: 0887-624X
    Keywords: aggregation ; emulusion polymerization ; flocculation ; latex ; particles ; polymer ; size distribution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The basic features of a three-step experimental process to produce supermicron polymer particles are described. First, a submicron emulsifier-free latex is prepared by a well-known technique. Second, the latex is aggregated by destabilizing with cetyl pyridinium chloride under constant stirring conditions, to yield roughly spherical clusters of 6-12 μ diameter. Third, the aggregates are stabilized with poly(vinyl alcohol) and internally coalesced by heating at or above the glass transition temperature. The final product particles have relatively smooth surfaces. Results are qualitatively interpreted in terms of a dynamic equilibrium where the aggregate size is determined by a balance between attractive interparticle potentials and stirring shear forces. Bimodal aggregate size distributions suggest the aggregate break-up mechanism may involve the erosion of individual latex particles and small fragments from the surface of aggregates. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1996.866
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  • 6
    Electronic Resource
    Electronic Resource
    An application of arene-iron chemistry in the synthesis of a novel liquid crystalline polymer (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 447-453 
    Details
    ISSN: 0887-624X
    Keywords: polyether ; polyester ; aryl ether ; nucleophilic substitution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arene-iron chemistry was applied in the synthesis of a novel liquid crystalline polymer. The chemistry, which is based on iron cyclopentadienyl (FeCp) arene complexes, allows sequential nucleophilic substitution of the chlorides from 1,3-dichlorobenzene-FeCp complex and photolytic decomplexation of the products to afford asymmetrical aryl ethers. This methodology provides easy access to novel polyether-esters, and is potentially useful in the synthesis of various functional polyarylates. © 1997 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    A comment on the paper “uniform polymer particles by dispersion polymerization in alcohol,” by C. M. Tseng, Y. Y. Lu, M. S. El-Aasser, and J. W. Vanderhoff [J. polym. sci. polym. chem. Ed. 24, 2995 (1986)]Presented, in part, at the NATO ASI on Polymer Colloids (Strasbourg, July 1988). This is Paper 5 in a series including Refs. 5-8 (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2569-2574 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280928
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  • 8
    Electronic Resource
    Electronic Resource
    Control of surfactant level in starve-fed emulsion polymerization. I. Sulfate-containing oligomers: Preparation and application as surfactant in emulsion polymerization (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1597-1606 
    Details
    ISSN: 0887-624X
    Keywords: emulsion polymerization ; surfactants ; oligomers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is well known that the amount of surfactant must be carefully controlled during starve-fed emulsion polymerization processes. Too little surfactant leads to emulsion instability and coagulation, while too much surfactant leads to secondary particle formation. Although these relationships are qualitatively understood in the art, there is little quantitative basis to guide the synthetic chemist, especially in multistep starve-fed emulsion polymerization processes to make larger supermicron particles. We have developed a method, which will be described in a companion article, to control the surfactant level by monitoring the surface tension during polymerization. In order to quantitatively predict how much surfactant to add at any given time, one needs to know in advance the adsorption characteristics of the soap. Further complicating the matter is the formation of “in situ” or oligomeric surfactant during polymerization with aqueous initiators such as ammonium persulfate.This work demonstrates how to prepare surface-active oligomers and how to make latex particles using them as surfactant. First, we established the mass balance for the initiator-derived sulfate groups in seed latexes by conductometric, potentiometric, and iodometric titrations. Based on the characterization of seed latexes, a method for determining the effective sulfate concentration has been developed. When surface-active oligomers were used as the only surfactant, we obtained a series of monodisperse, supermicron copolymer latex particles with diameters up to 3.22 μm. This is a similar result to that obtained with a commercially made anionic surfactant. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331006
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  • 9
    Electronic Resource
    Electronic Resource
    Dispersion polymerization of styrene in polar solvents. IV. Solvency control of particle size from hydroxypropyl cellulose stabilized polymerizationsPresented in part at the Canadian High Polymer Forum, Ottawa, August, 1987, and the NATO ASI on Polymer Colloids, Strasbourg, July, 1988; for Paper I of this series, see Ref. 1 (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2485-2500 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Changing solvent has a dramatic effect on the outcome of HPC stabilized dispersion polymerization of styrene in polar solvents. In methoxyethanol/ethanol mixtures, particle size varies from essentially infinity for unstabilized reactions (below 30% ethanol) to about 3 microns in ethanol. In a series of n-alcohols, there was a maximum in particle size at intermediate chain length: particle size increased from 2 microns in methanol to 8.3 microns in pentanol, then decreased again to 1 micron in octadecanol. These results were rationalized in terms of the three-component Hansen solubility parameters. The largest particles were obtained in solvents with Hanson polarity and hydrogen bonding terms closest to HPC. The generality of the three-component solubility parameter approach was examined by reactions performed in eight mixed solvents with the same values of all three Hansen terms. Seven of the eight solvents gave particles of similar size and molecular weight. The two critical effects of solvent on both particle size and molecular weight appear to be: (a) the solubility properties of the grafted HPC-PS formed, and (b) the partitioning of monomer and initiator between solution and particle phases subsequent to nucleation.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280921
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  • 10
    Electronic Resource
    Electronic Resource
    Thermal, mechanical, and fracture properties of copolyureas formed by reaction injection molding: Effects of hard segment structure (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1023-1039 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of copolyureas containing 50% by weight hard segment have been formed by RIM. The hard segment structure was systematically varied to investigate the effects of urea group density, hard segment crosslinking, relative reaction rates, and to compare the properties of aromatic and aliphatic hard segment materials. In each case the soft segment was based on a 2000 molecular weight polyether diamine. The RIM materials formed ranged from flexible elastomers to brittle plastics depending on composition and were characterized by SAXS, DSC, DMA, tensile stress-strain and fracture mechanics studies. SAXS, DSC, and DMA showed that microphase separation had occurred to give materials with a non-equilibrium morphology. DMA and tensile stress-strain studies showed the small strain properties to be very sensitive to the volume fraction of glassy material whereas the ultimate properties were dependent on chemical structure of the hard segment. Fracture properties were determined using the single-edge notch technique. In most cases ductile failure occurred with Gc 〉 2.5 kJ m-2 and the fracture surfaces showed gross yielding and tearing. In the case of the copolyurea with the highest urea group content, brittle fracture occurred with Gc = 0.06 kJ m-2.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420416
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