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  • Biochemistry and Biotechnology  (17)
  • Wiley-Blackwell  (17)
  • Springer Science + Business Media
  • 1
    Electronic Resource
    Electronic Resource
    Stabilization of substilisin E in organic solvents by site-directed mutagenesis (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 141-147 
    Details
    ISSN: 0006-3592
    Keywords: protein engineering ; enzymes in organic solvents ; protein stabilization ; subtilisin E ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Subtilisin E was rationally engineered to improve its stability in polar organic solvents such as dimethylformamide (DMF). A charged surface residue, Asp248, was substituted by three amino acids of increasing hydrophobicity, Asn, Ala, and Leu; all three variants were stabilized with respect to wild type in 80% DMF. This stabilization was only observed in the presence of high concentrations of the organic solvent: no stability enhancements were observed in 40% DMF. In contrast, the mutation Asn218 → Ser alters internal hydrogen bonding interactions and stabilizes subtilisin E in both 40% and 80% DMF. This study provides additional evidence that substitution of surface-charged residues is a generally useful mechanism for stabilizing enzymes in organic media and that the stabilizing effects of such substitutions are unique to highly altered solvent environments. The effects of the single amino acid substitutions on free energies of stabilization are additive in the Asp248 → Asn + Asn218 → Ser combination variant, yielding an enzyme that is 3.4 times more stable than wild type in 80% DMF.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260390204
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  • 2
    Electronic Resource
    Electronic Resource
    Organic acid production from CO2/H2 and CO/H2 by mixed-culture anaerobes (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 2293-2306 
    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 gases CO, CO2, and H2 were used as substrates in anaerobic fermentations producing organic acids. Various mixed bacterial sources were used, including sewage sludge digester effluent, rabbit feces, and soil. Nonsterile microorganism selection was carried out using CO2/H2 and CO/H2 as the primary carbon and energy sources. Cultures were grown in specially designed, high-pressure (to 70 psig) flasks. Methanogenic bacteria were eliminated from the cultures. Liquid products of the fermentations were acetic through caproic acids, with the even-numbered acids predominating. Carbon balances showed conclusively that acetic acid was formed from carbon contained in the CO or CO2 feed gas. Measurements made included rates of acid product formation, cell density, and degree of gas utilization. Limited characterization of the microorganisms was also performed. Production of organic acids by mixed culture inocula from CO2/H2 or CO/H2 had not been reported previously. Application of this work is to the production of organic chemicals from synthesis gas (SNG), produced by the gasification of fossil fuels (peat, lignite, and various ranks of coals), biomass (agricultural and forest residues, and various biomass crops grown expressly for energy recovery), and municipal solid waste.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260231012
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  • 3
    Electronic Resource
    Electronic Resource
    Enhanced release of rosmarinic acid from Coleus blumei permeabilized by dimethyl sulfoxide (DMSO) while preserving cell viability and growth (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 459-464 
    Details
    ISSN: 0006-3592
    Keywords: permeabilization ; dimethyl sulfoxide ; Coleus blumei ; preconditioning ; cell viability ; rosmarinic acid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous permeabilization of preconditioned Coleus blumei cells with dimethyl sulfoxide (DMSO) is shown to be an effective strategy for the enhanced release of rosmarinic acid (RA) while preserving cell viability. When nonpreconditioned cells were permeabilized with DMSO, they lost their viability at DMSO concentrations higher than a critical value located between 0.1% and 0.5% DMSO. Product release was low [0.49 g RA/100 g dry cell weight (DCW)] at 0.1% DMSO. Preconditioning cells at 0.1% DMSO ensured high viability at DMSO concentrations of 0.5%, 1.0%, and 1.5%. Product release reached a maximum of 2.85 g RA/100 g DCW at 0.5% DMSO, which was 66.4% of the total rosmarinic acid produced. © 1992 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260400403
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  • 4
    Electronic Resource
    Electronic Resource
    Stimulation of glucose catabolism through the pentose pathway by the absence of the two pyruvate kinase isoenzymes in Escherichia coli (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 58 (1998), S. 292-295 
    Details
    ISSN: 0006-3592
    Keywords: metabolic engineering ; carbon metabolism ; Escherichia coli mutants ; microbial growth ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Escherichia coli strains devoid of one or both of the two pyruvate kinase isoenzymes (PKA and PKF), were grown on minimal media in batch fermentations. The strain lacking both PKs showed a 28% decrease on its specific growth rate when compared to the wild type. However, protein and CO2 yields did not change. Using radioactive 1-C14 glucose and collecting the CO2 produced by the cultures, it was found that the mutant lacking both pyruvate kinases, metabolized glucose mainly through the pentose pathway (PP). The increased participation of the PP in glucose metabolism in this strain, was also reflected on the levels of the glucose-6-phosphate and 6-phosphogluconate dehydrogenases.© 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:292-295, 1998.
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Inhibition of the system luminol-H2O2-Fe(CN)63- chemiluminescence by the Mn(II) indirect determination of isoniazid in a pharmaceutical formulation (1998)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 131-137 
    Details
    ISSN: 0884-3996
    Keywords: chemiluminescence ; flow injection ; isoniazid ; solid-phase reactors ; pharmaceutical analysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A flow injection procedure for the indirect chemiluminescent determination of isoniazid is proposed. The method is performed in a flow-injection manifold provided with a solid-phase reactor. The reactor was made from manganese dioxide physically entrapped by polymerization; the redox reaction isoniazid-manganese dioxide released Mn(II) which was monitored through its inhibitory effect on the reaction between luminol and hydrogen peroxide in presence of potassium hexacyanoferrate(III). The procedure resulted in a linear calibration graph over the range 5-15 mg/L of isoniazid with a sample throughput of 43 samples/h. The influence of foreign compounds was studied and the method was applied to determination of the drug in a pharmaceutical formulation. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of cells' water membrane permeability: Unexpected high osmotic permeability of Saccharomyces cerevisiae (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 56 (1997), S. 62-70 
    Details
    ISSN: 0006-3592
    Keywords: osmotic shock ; water permeability ; mixing time constant ; mathematical model ; yeast ; leukemia K562 cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Water permeability (Lp), calculated from the volume variations of cells subjected to an osmotic shock, is classically used to characterize cell membrane properties. In this work, we have shown the importance of the kind of mixing reactor used to measure the Lp parameter. A mathematical model including the mixing time constant has been proposed allowing an accurate Lp estimation even though the mixing time constant is higher than the cell time constant obtained in response to a perfect shock. The estimated Lp values of human leukemia K562 cells were found to be the same whatever the mixing time constant. The Lp value of Saccharomyces cerevisiae could not be exactly estimated. However, S. cerevisiae has unexpectedly high water permeability, implying that this yeast may contain water channels in the membrane. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 62-70, 1997.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and conformational studies of peptides containing TOAC, a spin-labelled Cα,α-disubstituted glycine (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 1 (1995), S. 45-57 
    Details
    ISSN: 1075-2617
    Keywords: β-bend ; 310-helix ; peptide conformational analysis ; spin-labelled amino acid ; TOAC peptides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variety of host L-alanine homo-peptides (to the pentamer) containing one or two spin-labelled TOAC (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) residues were synthesized by solution methods and fully characterized. The conformational features of the terminally blocked, doubly spin-labelled-TOAC-(Ala)2-TOAC-Ala- pentapeptide were examined in the crystal state by X-ray diffraction and in solution using a combination of techniques (Fourier transform infrared, circular dichroism, cyclic voltammetry and electron spin resonance) in comparison with singly labelled shorter peptides. The 310-helical structure of the pentapeptide, promoted by the two Cα,α-disubstituted glycines under favourable experimental conditions, allows an interaction to take place between the two nitroxide TOAC side chains spaced by one turn of the helix. Taken together, these results suggest that TOAC is an excellent probe for exploring bends and helices in doubly labelled peptides.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.310010107
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  • 8
    Electronic Resource
    Electronic Resource
    The use of N-urethane-protected N-carboxyanhydrides (UNCAs) in amino acid and peptide synthesis (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 1 (1995), S. 124-131 
    Details
    ISSN: 1075-2617
    Keywords: β-amino-alcohol ; statine ; UNCAs ; vicinal tricarbonyl compounds ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Urethane-protected N-carboxyanhydrides (UNCAs) are very reactives. They have been successfully used in peptide synthesis, in both solution and solid phase. We have demonstrated that UNCAs are interesting starting materials for the synthesis of various amino acid derivatives. Chemoselective reduction of UNCAs with sodium borohydride led the corresponding N-protected β amino alcohols. Reaction of UNCAs with Meldrum's acid, followed by cyclisation, yielded enantiomerially pure tetramic acid derivatives. Diastereoselective reduction of tetramic acid derivatives produced (4S,5S)-N-alkoxycarbonyl-4-hydroxy-5-alkylpyrrolidin-2-ones derived from amino acids, which after hydrolysis yielded statine and statine analogues. Tetramic acid derivatives could also be obtained by reaction of UNCAs with benzyl ethyl followed by hydrogenolytic deprotection and decarboxylation. UNCAs also reacted with phosphoranes to produce the ketophosphorane in excellent yields. Subsequent oxidation with oxone or with [bis(acetoxy)-iodol]-benzene produced vicinal tricarbonyl derivatives. These reactions usually proceeded smoothly and with high yields.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.310010204
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  • 9
    Electronic Resource
    Electronic Resource
    Action of endogenous proteases on the distribution of tyrosinase isozymes in Harding-Passey mouse melanoma (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 7 (1989), S. 21-26 
    Details
    ISSN: 0263-6484
    Keywords: Tyrosinase ; melanoma ; tumour proteases ; melanosome degradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A high percentage of the total tyrosinase found in Harding-Passey mouse melanoma occurs as a soluble form. This paper shows that melanosomal tyrosinase can be solubilized by several endogenous proteases to yield active tyrosinase. This enzyme, once proteolitically solubilized, can be further degraded, leading to enzyme inactivation. The nature and specificity of the main proteases involved in the solubilization process change depending on the size and necrosis stage of the tumour. Cathepsin B could be the main protease responsible for the solubilization in small tumours (〈 0·5 g). Large tumours are rich in necrotic cells, and cathepsin D and serine-proteases are the main hydrolytic enzymes involved in the proteolytic action on mealanosomes. These results support the view that the high activity of tyrosinase found in the soluble fraction of malignant melanoma is mainly an artefact resulting from degradation of melanosomes by a variety of endogenous proteases, rather than the result of the actual occurrence of high levels of an independent cytosolic isozyme.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cbf.290070105
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  • 10
    Electronic Resource
    Electronic Resource
    Two-dimensional electrophoresis of human placental mitochondria and protein identification by mass spectrometry: Toward a human mitochondrial proteome (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1006-1014 
    Details
    ISSN: 0173-0835
    Keywords: Two-dimensional polyacrylamide gel electrophoresis ; Silver staining ; Mass spectrometry ; Proteome ; Mitochondria ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Owing to the complexity of higher eukaryotic cells, characterization of a complete proteome is likely to be difficult to achieve. However, advantage can be taken of the cell compartmentalization to build organelle proteomes, which can moreover be viewed as specialized tools to study specifically the biology and “physiology” of the target organelle. Within this frame, we report here the construction of the human mitochondrial proteome, using placenta as the source tissue. Protein identification was carried out mainly by peptide mass fingerprinting, but other methods were also used (N-terminal microsequencing, blotting). The optimization steps in two-dimensional (2-D) electrophoresis needed for proteome research are discussed. However, the relative paucity of data concerning mitochondrial proteins is still the major limiting factor in building the corresponding proteome, which should be a useful tool for researchers working on human mitochondria and their deficienciesThis work can be found on the Internet at the following address: http://www-dsv.cea.fr/MitoPick/Default.html.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190616
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