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  • 1
    Electronic Resource
    Electronic Resource
    Crystal structures of two mutants of adenylate kinase from Escherichia coli that modify the Gly-loop (1993)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 15 (1993), S. 42-49 
    Details
    ISSN: 0887-3585
    Keywords: X-ray structure ; ATP-binding proteins ; glycine-rich loop ; enzyme kinetics ; induced-fit ; H-ras-p21 relationship ; crystal packing contacts ; noncrystallographic symmetry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Two mutants of adenylate kinase from Escherichia coli have been crystallized and analyzed by X-ray diffraction at resolutions of 3.4 and 2.4 Å, respectively. These mutants are Pro-9→Leu and Gly-10→Val. They were selected for their positions in the highly conserved Gly-loop forming a giant anion hole for the β-phosphate of ATP (GTP) in adenylate kinases, H-ras-p21, and other nucleotide-binding proteins. Mutants at these positions of H-ras-p21 cause cancer. In adenylate kinase these mutations cause smallish changes at the active site. Relating the structural changes to the known changes in catalysis indicates that these mutants hinder the induced-fit movements. As a side result we find that mutant Pro-9→Leu and wild-type form one very similar crystal packing contact that is crystallographic in one case and noncrystallographic in the other, while all other packing contacts and the space groups are quite at variance. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340150106
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  • 2
    Electronic Resource
    Electronic Resource
    Hydroxynitrile lyase from Hevea brasiliensis: Molecular characterization and mechanism of enzyme catalysis (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 27 (1997), S. 438-449 
    Details
    ISSN: 0887-3585
    Keywords: α/β hydrolase fold ; catalytic triad ; cyanolysis ; heterologous expression ; Saccharomyces cerevisiae ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: (S)-Hydroxynitrile lyase (Hnl) from the tropical rubber tree Hevea brasiliensis is a 29 kDa single chain protein that catalyses the breakdown or formation of a C(SINGLE BOND)C bond by reversible addition of hydrocyanic acid to aldehydes or ketones. The primary sequence of Hnl has no significant homology to known proteins. Detailed homology investigations employing PROFILESEARCH and secondary structure prediction algorithms suggest that Hnl is a member of the α/β hydrolase fold protein family and contains a catalytic triad as functional residues for catalysis. The significance of the predicted catalytic residues was tested and confirmed by site-directed mutagenesis and expression of mutant and wild-type proteins in the yeast, Saccharomyces cerevisiae. Based on these data we suggest a mechanistic model for the (S)-cyanohydrin synthesis catalyzed by hydroxynitrile lyase from Hevea brasiliensis. Proteins 27:438-449, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Simultaneous utilization of methanol-glucose mixtures by Hansenula polymorpha in chemostat: Influence of dilution rate and mixture composition on utilization pattern (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1735-1741 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The utilization of mixtures of methanol (C1) and glucose (C6) of different composition by the methylotrophic yeast Hansenula polymorpha was studied in carbon-limited chemostat culture. For all mixtures tested a similar utilization pattern was observed: At low dilution rates both carbon sources were utilized simultaneously, but at high dilution rates the cells used glucose only and the unutilized methanol accumulated in the culture medium. When grown with C1 only, the cells exhibited a critical dilution rate Dc(C1) of 0.19 h-1, but when C1-C6 mixtures were used as the carbon and energy substrate, the yeast was able to completely utilize C1 at dilution rates considerably higher than Dc(C1). The dilution rate at which the transition from C1-C6 growth to C6 growth occurred (Dt) was strictly dependent on the composition of the C1-C6 mixture in the feed, and Dt increased with decreasing proportions of C1 in the mixture. During mixed substrate growth the formation of biomass from the two substrates was additive. The results reported indicate that the utilization of C1-C6 mixtures and hence Dt in H. polymorpha are subject to two different regulatory regimes. When the cells were growing with C1-C6 mixtures containing more than 60% C1, the transition form C1-C6 to C6 growth was most probably influenced by the maximum C1 oxidizing capacity of the cells, whereas for growth with mixtures containing less than 40% C1, a growth rate of 0.28-0.30 h-1 seemed to be the limiting barrier for the simultaneous utilization of the components of the binary carbon and energy substrate mixture.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260281118
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  • 4
    Electronic Resource
    Electronic Resource
    Low multiplicity infection of insect cells with a recombinant baculovirus: The cell yield concept (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 659-666 
    Details
    ISSN: 0006-3592
    Keywords: suspension culture ; insect cells ; baculovirus ; multiplicity of infection ; time of infection ; model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In vitro infection of insect cells with baculoviruses is increasingly considered a viable means for the production of biopesticides, recombinant veterinary vaccines, and other recombinant products. Batch fermentation processes traditionally employ intermediate to high multiplicities of infection necessitating two parallel scale-up processes - one for cells and one for virus. In this study, we consider the use of multiplicities of infection as low as 0.0001 plaque-forming units per cell, a virus level low enough to enable infection of even large reactors (e.g., 10 m3) directly from a frozen stock. Using low multiplicities in the Sf9/β-gal-AcNPV system, recombinant protein titers comparable with the maximum titer observed in high multiplicity infections were achieved. Cultures yielding the maximum titer were characterized by reaching a maximum cell density between 3 and 4 × 109 cell L-1. This optimal cell yield did not depend on the multiplicity of infection, supporting the existing view that batch cultures are limited by availability of substrate. Up to a certain cell density, product titer will increase almost linearly with availability of biocatalyst, that is, cells. Beyond this point any further cell formation comes at the expense of final product titer. Low multiplicity infections were found not to cause any significant dispersion of the protein production process. Hence, product stability is not a major issue of concern using low multiplicities of infection. The sensitivity to initial conditions and disturbances, however, remains an issue of concern for the commercial use of low multiplicity infections. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    DNA binding properties of minor groove binders and their influence on the topoisomerase II cleavage reaction (1997)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 10 (1997), S. 245-255 
    Details
    ISSN: 0952-3499
    Keywords: RY-repeat ; minor groove binders ; topoisomerase II cleavage ; footprinting ; microscopic binding constants ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We present titrations of the human δβ-globin gene region with DNA minor groove binders netropsin, bisnetropsin, distamycin, chromomycin and four bis-quaternary ammonium compounds in the presence of calf thymus topoisomerase II and DNase I. With increasing ligand concentration, stimulation and inhibition of enzyme activity were detected and quantitatively evaluated. Additionally we show a second type of stimulation, the appearance of strong new topoisomerase II cleavage sites at high ligand concentrations. The specific binding sites of the minor groove binders of the DNA sequence and their microscopic binding constants were determined from DNase I footprints. A binding mechanism for minor groove binders is proposed in order to explain these results especially when ligand concentration is increased. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Partitioning of low molecular combination peptides in aqueous two-phase systems of poly(ethylene glycol) and dextran in the presence of small amounts of K2HPO4/KH2PO4 buffer at 293 K: Experimental results and predictions (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 699-711 
    Details
    ISSN: 0006-3592
    Keywords: aqueous two-phase systems ; partitioning of peptides ; liquid-liquid phase equilibrium ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Buffered aqueous two-phase systems are effective extraction systems for separating amphoteric hydrocarbons like, for example, polypeptides from aqueous phases. The design and basic engineering of such processes requires the knowledge of the liquid-liquid equilibrium. The study presented here aims to contribute to the development of methods to predict the partitioning of peptides in aqueous two-phase systems. Experimental results are reported for the partitioning of small amounts (≈0.001 g solute per gram of solution) of low molecular combination peptides of glycine, L-glutamic acid, L-phenylalanine, and L-lysine (9 dipeptides, gly-glu, gly-phe, gly-lys, glu-gly, phe-gly, phe-glu, lys-gly, lys-glu, lys-phe; 7 tripeptides, gly-gly-phe, gly-phe-gly, glu-gly-phe, phe-gly-gly, lys-gly-lys, lys-glu-gly, lys-phe-lys) in aqueous two-phase systems of high molecular weight dextran (molecular weight about 500,000) and poly(ethylene glycol) (molecular weight about 6,000 and 35,000, respectively) in the presence of small amounts (about 0.05 mol/kg) of K2HPO4/KH2PO4 buffer at about 293 K. The new data are compared to predictions. Partition coefficients are predicted applying a group contribution excess Gibbs energy model. The model is an osmotic virial equation. It uses surface fractions to encounter for the probability of interactions between solutes. All model parameters were taken from the literature. They were determined exclusively from experimental data for the phase forming systems and for the partitioning of amino acids and their di- and tripeptides (containing only a single amino acid), but no experimental data for the partitioning of combinations peptides were used. In most cases predicted partition coefficients agree favourably with the experimental data. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 699-711, 1998.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Blotting efficiency investigated by using two-dimensional electrophoresis, hydrophobic membranes and proteins from different sources (1990)
    Weinheim : Wiley-Blackwell
    Electrophoresis 11 (1990), S. 581-588 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Purification and chemical characterization of protein may be achieved by combining two-dimensional electrophoresis (2-DE) and microsequencing or amino acid analysis. To enable this combination, the protein has to be transferred as completely as possible from the gel into the sequencer. In this study hydrophobic membranes were used as support for the transfer and proteins were transferred from the gels onto the membranes by semidry blotting. Blotting conditions were optimized to obtain high blotting efficiencies for as many proteins of a complex 2-DE pattern as possible. Under optimized conditions, blotting efficiencies between 60 % and 100 % were obtained for five marker proteins; the mean values from four regions of a 2-DE pattern from 29 unknown proteins of a complex protein mixture from mouse brain were between 60 % and 79 %. The four commercially available hydrophobic membranes that were compared showed only slight differences in protein amount on the membranes after blotting for whole protein patters, whereas single proteins occurred with higher amounts on either one or the other membrane. The results of the blotting optimization allowed us to suggest a blotting mechanism with which systematic improvement of the blotting conditions is possible for problematic proteins.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150110709
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  • 8
    Electronic Resource
    Electronic Resource
    Continuous focusing of biological particles by continuous immuno magnetic sorter: Technique and applications (1995)
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 789-792 
    Details
    ISSN: 0173-0835
    Keywords: Free-flow magnetophoresis ; Magnetic sorting ; Continuous immuno magnetic sorter ; Viable cell sorting ; Blood cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We have developed a device for continuous deviation-mode, open-gradient fractionation of strongly magnetizable particles based on an electrophoresis counter-flow chamber. A mixture of magnetically labeled and nonlabeled particles can be injected into a given continuously flowing chamber buffer. The particles pass the inhomogeneous magnetic field of the open-gradient electromagnet in two narrow streams. According to the magnetic moments, induced by the magnetic field, magnetically labeled particles are deviated. The nonlabeled particles pass the magnetic field with negligible interaction. The deviated particles are focused into a stream that is completely separated from the streams of the nondeviated particles. The streams are fractionated by the counter-flow technique and collected in different vials. A high sorting purity, depending only on the specificity of the antibodies or similar labeling techniques, and a high through-put rate of up to 109 particles per hour was achieved. This was experimentally shown both by test particles and blood cells. The vital conditions of these blood cells were maintained by magnetic sorting.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501601129
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  • 9
    Electronic Resource
    Electronic Resource
    The use of restriction landmark genomic scanning to scan the mouse genome for endogenous loci with imprinted patterns of methylation (1995)
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 210-217 
    Details
    ISSN: 0173-0835
    Keywords: Genomic imprinting ; Restriction landmark genomic scanning ; U2afbp-rs ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Restriction landmark genomic scanning (RLGS) has been used to screen endogenous loci for imprinted patterns of methylation. The screening method is based upon the identification of genetic variation in RLGS profiles between different strains and determining whether specific variant landmarks are transmitted equally to the progeny of reciprocal F1 matings. The RLGS profiles of C57BL/6 (B6) and DBA/2 (D2) and their reciprocal hybrids were produced with two enzyme combinations that used NotI as the landmark enzyme and two combinations that used BssHII. An estimated 13% of the spots are either B5- or D2-specific in these tests, giving a total of nearly 1000 variant loci that were examined for imprinted methylation. Three candidate loci for imprinted regulation were identified in these analyses. We also used crosses of more genetically diverse parents to increase the number of variant loci screened. Interspecific crosses of B6 with the M. musculus strain PWK and intrasubspecific crosses between B6 and the M. molossinus strain MSM expanded the levels of variation between the parental strains in the cross to an estimated 31% and 26%, respectively. The RLGS patterns for one NotI combination and one BssHII profile were examined for each of these crosses, giving approximately 2000 additional loci that were screened for imprinted patterns of methylation. Eight loci with imprinted patterns of transmission were observed out of 3040 loci tested. The chromosomal locations for the three B6 and D2 specific loci, Irlgs 1-3, were identified using BXD recombinant inbred strain analysis. Irlgs 1 and 3 are B6- and D2-specific loci that had the same strain distribution pattern which mapped to the central region of chromosome 9. Irlgs 2 (U2afbp-rs) was mapped to the proximal region of chromosome 11, which was reported as an imprinted region identified with uniparental disomy mice. An imprinted gene, U2 auxiliary factor binding protein-related sequence (U2afbp-rs), was identified for Irlgs2 locus, which encoded 51 kDa protein that had significant homology to the human U2af 35 kDa small subunit.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150160136
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  • 10
    Electronic Resource
    Electronic Resource
    Genetic mapping of restriction landmark genomic scanning loci in the mouse (1995)
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 233-240 
    Details
    ISSN: 0173-0835
    Keywords: Genetic mapping ; Mouse ; Restriction landmark genomic scanning ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Restriction landmark genomic scanning (RLGS) was originally proposed as a high-speed method for surveying a large number of restriction landmarks in genomic DNA. The effort to apply this method to genetic analysis has been made, resulting in developing the new approach for the rapid construction of the genetic map of complex mammalian genomes (RLGS spot mapping). Especially, the use of NotI as the restriction landmark for genetic studies suggests that there is a high probability that a significant number of these RLGS loci will be associated with CpG islands of functional genes. Moreover, it is possible to use the RLGS spot mapping to analyze genetic map-poor species very rapidly for linkage of recessive mutations or segregating traits, because it does not rely upon cloned probes or sequences. In this paper, we summarize the progress that has been made in the practical application of the RLGS method to genetic analysis using congenic strains, recombinant inbred (RI) strains, and in interspecific backcrosses of mice.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150160139
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