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  • 1
    Electronic Resource
    Electronic Resource
    Mutant Escherichia coli penicillin acylase with enhanced stability at alkaline pH (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 141-148 
    Details
    ISSN: 0006-3592
    Keywords: protien stability ; protein surface charge ; 6- amino-penicillanic acid ; biocatalysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Increased stability at alkaline pH should be a valuable attribute for the utilization of penicillin acylase in bioreactors employed to convert penicillins into 6-aminopenicillanic acid, a precursor of semisynthetic penicillins. In these systems, base is added for pH control, which results in local alkaline conditions that promote enzyme inactivation. Hydrolysis and synthesis reactions are also pH dependent. Here, we report work in which the gene coding for Escherichia coli penicillin acylase was subjected to oligonucleotide-directed random mutagenesis at regions coding for amino acids predicted to be at the surface of the enzyme. The resulting mutant library, cloned in E. coli, was screened by a filter paper assay of the colonies for the presence of penicillin acylase activity with enhanced stability at alkaline pH. Characterization of one of the selected clones revealed the presence of a mutation, Trp431-Arg, which would presumably alter the surface charge of the protein. In vitro experiments demonstrated a near twofold increase in the half-life of the mutant enzyme when stored at pH 8.5 as compared with the wild-type enzyme, with a comparable specific activity at several pH values. In general, the mutant displayed increased stability toward the basic side in the pH-stability profile. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260480208
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  • 2
    Electronic Resource
    Electronic Resource
    Electrophoretic human leukocyte antigen HLA-DQA1 DNA typing after polymerase chain reaction amplification (1991)
    Weinheim : Wiley-Blackwell
    Electrophoresis 12 (1991), S. 1041-1045 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: An electrophoretic method (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) is described which permits the identification of human leukocyte antigen HLA-DQA1 types and subtypes without using allele-specific oligonucleotide prodes and dot-blot methodology. The procedure can be used in miniaturized gels in combination with automated electrophoretic systems. The PhastSystem is particularly recommended since temperature contol is essential. HLA-DQA1*1 and DQA1*0301 can be distinguished in homoduplexes and DQA1*01 subtypes, DQA1*201 and DQA1*0401 in heteroduplexes (in only 5 including DNA extraction and PCR amplification). Additional variations to those recognized using commercially available dot-blot methods can be provided since this this procedure permits the identification of single base-pair substitutions. In addition, this method is faster and less expensive than commercial methods.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150121208
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  • 3
    Electronic Resource
    Electronic Resource
    A 33 kDa protein band in enhanced during long-term adaptation of EUE cells to a hypertonic medium (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 9 (1991), S. 87-94 
    Details
    ISSN: 0263-6484
    Keywords: Hypertonic stress ; EUE cells ; SDS-PAGE ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A cell line derived from human embryonic epithelium (EUE cells) shows an enhanced expression of a 33 kDa protein when adapted to grow in a hypertonic medium containing 0·246 M NaCl (1·8 × the isotonic concentration). The maximum amount of this protein, followed by SDS-PAGE electrophoresis, was found after 4 days of adaptation; thereafter, the protein band remained fairly constant up to 30 days. When the cells were transferred back to a medium containing 0·137 M NaCl (isotonic medium), the protein pattern reverted to that of control cells. This protein is mainly localized in the cytosol, although a small part is associated with the 150 000 g pellet and needs detergents to be extracted. The molecular weight and the cellular location suggest a possible analogy with the so-called amphitropic proteins, that are known to interact with both the epidermal growth factor receptor and hydrophobic structures, such as the membrane phospholipids and the cytoskeletal components.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cbf.290090204
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  • 4
    Electronic Resource
    Electronic Resource
    Double- and single-strand conformation polymorphism analysis of point mutations and short tandem repeats (1994)
    Weinheim : Wiley-Blackwell
    Electrophoresis 15 (1994), S. 566-571 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Single point mutations in small DNA fragments and single unit differences in simple repetitive DNA can be detected as double-strand conformation polymorphisms using polyacrylamide gel electrophoresis, with and without sodium dodecyl sulfate, even at temperatures as low as 3°C. Changes in a single base are distinguished by means of the analysis of the heteroduplexes, and changes in more than two bases can be distinguished in both homoduplexes and heteroduplexes. Polymerase chain reaction (PCR) conditions can be designed not only to amplify homoduplexes, heteroduplexes and singlestrand DNA at the same time, but also to focus the analysis on either singlestrand conformation polymorphism (SSCP) or double-strand conformation polymorphism (DSCP). DSCP seems to be advantageous in typing DNA polymorphisms or mutations in loci with few variants, but, because it is necessary to have a simple pattern of all possible combinations of the alleles, it is not as advantageous in typing systems with many variants.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150150177
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  • 5
    Electronic Resource
    Electronic Resource
    New synthesis of cyclic AMP-dependent protein kinases during liver regeneration (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 6 (1988), S. 203-208 
    Details
    ISSN: 0263-6484
    Keywords: Protein kinases ; calmodulin ; partial hepatectomy ; liver regeneration ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: As has been previously reported one surge in cytosolic calmodulin is produced between 4 and 12 h after a partial hepatectomy. Moreoever, a surge in cytosolic cyclic AMP and another in cyclic AMP-dependent protein kinase activity can be detected during the late period of the prereplicative phase of liver regeneration after a partial hepatectomy. It is known that these three surges are involved in triggering DNA synthesis.By kinetic studies and by injecting transcription (actinomycin D) and translation (cycloheximide) inhibitors into hepatectomized rats we have demonstrated that the cyclic AMP-dependent protein kinase surge is produced by new synthesis of the enzyme. In thyroparathyroidectomized rats subjected to a partial hepatectomy the calmodulin surge was similar to that observed in normal hepatectomized rats whereas the surge in cyclic AMP-dependent protein kinase activity was strongly decreased suggesting that the cyclic AMP-dependent protein kinase surge is not generated by the previous surge in calmodulin.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cbf.290060309
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  • 6
    Electronic Resource
    Electronic Resource
    Inositolphosphoglycans possibly mediate the effects of glucagon-like peptide-1(7-36)amide on rat liver and adipose tissue (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 16 (1998), S. 51-56 
    Details
    ISSN: 0263-6484
    Keywords: GLP-1 ; inositolphosphoglycans (IPGs) ; glycosylphosphatidylinositols (GPIs) ; hepatocytes ; adipocytes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Insulin-like effects of glucagon-like peptide-1(7-36)amide (GLP-1) in rat liver, skeletal muscle and fat, and also the presence of GLP-1 receptors in these extrapancreatic tissues, have been documented. In skeletal muscle and liver, the action of GLP-1 is not associated with an activation of adenylate cyclase, and in cultured murine myocytes and hepatoma cell lines, it was found that GLP-1 provokes the generation of inositolphosphoglycan molecules (IPGs), which are considered second messengers of insulin action. In the present work, we document in isolated normal rat adipocytes and hepatocytes that GLP-1 exerts a rapid decrease of the radiolabelled glycosylphosphatidylinositols (GPIs) - precursors of IPGs - in the same manner as insulin, indicating their hydrolysis and the immediate short-lived generation of IPGs. Thus, IPGs could be mediators in the GLP-1 actions in adipose tissue and liver, as well as in skeletal muscle, through GLP-1 receptors which are, at least functionally, different from that of the pancreatic B-cell. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chiral separation of polychlorinated biphenyls by micellar electrokinetic chromatography with sodium cholate (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2113-2118 
    Details
    ISSN: 0173-0835
    Keywords: Micellar electrokinetic chromatography ; Bile salts ; Sodium cholate ; Polychlorinated biphenyls ; Enantiomeric separations ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Micellar electrokinetic chromatography (MEKC) with one kind of bile salt (sodium cholate) was used to separate three chiral polychlorinated biphenyls (PCBs; 84, 95, and 176), each one in its two enantiomers. Sodium cholate was used as chiral surfactant in a 2-(N-cyclohexylamino) ethanesulfonic acid (CHES) buffer under alkaline (pH 10) conditions containing urea (2 M). The influence of bile salt concentration on the efficiency and the resolution between the two enantiomers of PCBs 84 and 95 was established. The chiral separation of three PCBs was successfully achieved in less than 30 min (approximately 23 min for PCB 176 and approximately 29 min for PCBs 84 and 95).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191212
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of methotrexate (MTX) on NAD(P)+ dehydrogenases of HeLa cells: malic enzyme, 2-oxoglutarate and isocitrate dehydrogenases (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 15 (1997), S. 259-264 
    Details
    ISSN: 0263-6484
    Keywords: methotrexate ; antineoplasic drug ; isocitrate dehydrogenase ; 2-oxoglutarate dehydrogenase ; malic enzyme ; HeLa cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of methotrexate (MTX) on oxygen uptake by permeabilized HeLa cells were evaluated. MTX did not inhibit state III respiration when the oxidizable substrate was succinate, but when the substrates were 2-oxoglutarate or isocitrate the respiration decreased about 50 per cent at 1·0 mM concentration of the drug. This effect was explained by inhibition of 2-oxoglutarate and isocitrate dehydrogenases by MTX. No effect was observed on succinate dehydrogenase. An evaluation of the effects of MTX on malic enzyme activity as measured by pyruvate plus lactate production in intact cells supplied with malate showed a decrease of about 40 per cent in metabolite production using 0·4 mM MTX. HeLa cell malic enzyme, as observed for other tumour cells, is compartmentalized in mitochondria and cytosol, and is another example of a dehydrogenase inhibited by MTX. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Rat urinary chemiluminescence: effect of ethanol and/or hexachlorobenzene uptake (1998)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 63-68 
    Details
    ISSN: 0884-3996
    Keywords: ethanol ; hexachlorobenzene ; porphyria ; oxidative stress ; spontaneous urinary chemiluminescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Hexachlorobenzene (HCB) administration to rats induces porphyria cutanea tarda, characterized by high levels of urinary porphyrins (〉40 μg/day) and accumulation of highly carboxylated porphyrins in liver (〉15 μg/g of tissue). Ethanol administration, under the conditions employed, was not porphyrinogenic and was able to diminish some of the responses elicited by HCB. Furthermore, ethanol and/or HCB administration leads to organ disturbances that involve oxidative stress. We have measured the changes in urinary chemiluminescence (CL) levels, as part of a systematic evaluation of the metabolic alterations in rats chronically treated with ethanol and/or HCB. The results, that constitute the first set of urinary CL data obtained from an animal model system, indicate that the measurement of the spontaneous urinary CL can constitute a fast, simple and sensitive method to evaluate disturbances associated with oxidative stress. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Sandy alumina as substrate for economic and highly efficient immobilization of β-glucosidase (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 777-779 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260330615
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