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  • 1
    Electronic Resource
    Electronic Resource
    Optimization of alkyl β-D-galactopyranoside synthesis from lactose using commercially available β-galactosidases (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 657-666 
    Details
    ISSN: 0006-3592
    Keywords: β-galactosidase ; lactose ; β-galactopyranoside ; synthesis ; organic solvent ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Commercially available lactase (β-D-galactoside galactohydrolase, EC 3.2.1.23) enzymes produced from Kluyveromyces fragilis and Kluyveromyces lactis were accessed as catalysts for use in the production of β-galactopyranosides of various alcohols using lactose as galactosyl donor. The yield of galactoside was enhanced by using the highest practical concentrations of both lactose and alcohol acceptor. The concentrations and thus yield, were limited by the solubility of the substrates. The increase in galactoside yield with increasing lactose concentration appeared to be specific to the lactose substrate and not due to water activity alterations, because addition of maltose to a fixed concentration of lactose had no effect. During the course of the reaction, the yield of galactoside peaked after around 70% to 80% of the lactose was consumed, due to hydrolysis of the product by the enzyme. A wide variety of compounds with primary or secondary hydroxyl groups could act as acceptors, the essential requirement being at least some water solubility. Addition of organic cosolvents had little effect on galactoside yield except when it increased the water solubility of sparingly soluble alcohols. Some galactosides were synthesized on a gram scale to determine practical product recoveries and improve purification methods for large-scale synthesis. Initial purification by hydrophobic chromatography (for galactosides of hydrophobic alcohols) or strong anion-exchange chromatography (for galactosides of hydrophilic alcohols) separated galactosides, galactobiosides, and higher oligomers from reducing sugars. A facile separation of the galactoside and galactobioside could then be effected by flash chromatography on silica gel. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420514
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  • 2
    Electronic Resource
    Electronic Resource
    Papain in organic solvents: Determination of conditions suitable for biocatalysis and the effect on substrate specificity and inhibitionNRCC Publication No. 32406. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 519-527 
    Details
    ISSN: 0006-3592
    Keywords: papain ; organic solvent ; ester synthesis ; enzyme inactivation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Synthesis of N-CBZ-(N-Carbobenzoxy)-1-amino-acid methyl esters from N-CBZ-amino acids and methanol has been used as an assay to examine the properties of papain in organic solvents containing small amounts of water. Papain is active in solvents ranging in polarity from acetonitrile to tetrachloromethane. The optimal activity in each solvent varied only about three to four fold, but the amount of added water required to achieve it varied from 4% (v/v) in acetonitrile to 0.05% (v/v) in tetrachloromethane. The enzyme was generally more stable in hydrophobic solvents and at lower water contents. The apparent Km value of CBZ-glycine was 26 times higher in acetonitrile than in toluene due to differential partitioning of the substrate between aqueous and organic phases. The substrate specificity of the enzyme was qualitatively little different from that in aqueous solution, with amino acid derivatives still the best substrates. Nitrile analogs of substrates inhibited the enzyme, as they do in aqueous solution, and inhibition by a variety of substituted aromatic hydrocarbons showed that the main specificity of papain for hydrophobic side chains at its S2 subsite, was little affected. The results show that papain can catalyze reactions under a variety of conditions in organic solvents but its substrate specificity is little changed from that in aqueous media.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260370605
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  • 3
    Electronic Resource
    Electronic Resource
    Solution structure of a core peptide derived from scyllatoxin (1994)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 18 (1994), S. 205-215 
    Details
    ISSN: 0887-3585
    Keywords: peptide folding ; disulfide framework ; insect toxins ; NMR ; distance geometry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: An analysis of the sequences of scyllatoxin and charybdotoxin suggested that it would be possible to design a core peptide sequence which would still fold to give the β-hairpin and helix seen in the toxins, but which would eliminate one disulfide and connecting residues. The core sequence was modeled, then synthesized and purified. The cysteines oxidize in air to give the same disulfide pairings as seen in the parent toxins as the major product. The three-dimensional structure of the core sequence peptide, termed Max, was determined using proton NMR spectroscopy and found to be identical in secondary structure to the toxins. However differences were found in the relative orientation of the β-hairpin and helix. The use of this structural motif, found in many insect toxins, as a disulfide framework for exploring sequence/structure/activity relationships is discussed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340180302
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  • 4
    Electronic Resource
    Electronic Resource
    Flexible docking using tabu search and an empirical estimate of binding affinity (1998)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 33 (1998), S. 367-382 
    Details
    ISSN: 0887-3585
    Keywords: ligand-protein docking ; molecular recognition ; tabu search ; empirical scoring function ; binding affinity prediction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This article describes the implementation of a new docking approach. The method uses a Tabu search methodology to dock flexibly ligand molecules into rigid receptor structures. It uses an empirical objective function with a small number of physically based terms derived from fitting experimental binding affinities for crystallographic complexes. This means that docking energies produced by the searching algorithm provide direct estimates of the binding affinities of the ligands. The method has been tested on 50 ligand-receptor complexes for which the experimental binding affinity and binding geometry are known. All water molecules are removed from the structures and ligand molecules are minimized in vacuo before docking. The lowest energy geometry produced by the docking protocol is within 1.5 Å root-mean square of the experimental binding mode for 86% of the complexes. The lowest energies produced by the docking are in fair agreement with the known free energies of binding for the ligands. Proteins 33:367-382, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulations of the cytochrome c3-rubredoxin complex from Desulfovibrio vulgaris (1991)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 11 (1991), S. 142-152 
    Details
    ISSN: 0887-3585
    Keywords: AMBER ; electrostatics ; protein-protein interactions ; intermolecular bonding ; electron transfer ; redox proteins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Molecular dynamics simulations have been carried out on the complex formed between the tetraheme cytochrome c3 and the iron protein rubredoxin from the sulfate-reducing bacterium Desulfovibrio vulgaris. These simulations were performed both with explicit solvent water molecules included, and without solvent molecules using a distance-dependent dielectric constant to approximate the screening effects of solvent. The results of both simulations are strikingly different, indicating that the representation of environmental effects is important in such simulations. For example, a striking adaptation of the two proteins seen in the nonsolvated simulation is not seen when explicit solvent water is included; in fact, the complex appears to become weaker in the solvated simulation. Nonetheless, the iron-iron distance decreases more significantly in the solvated simulation than in the nonsolvated simulation. It was found that in both cases molecular dynamics optimized the structures further than energy minimization alone.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340110207
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  • 6
    Electronic Resource
    Electronic Resource
    A comparison of the immunogenicity of a pair of enantiomeric proteins (1993)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 16 (1993), S. 306-308 
    Details
    ISSN: 0887-3585
    Keywords: rubredoxin ; lgG antibody ; lgM antibody ; immunogen ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The immunogenicity of a folded, all D-amino acid protein- rubredoxin, has been compared with that for the corresponding L-protein enantiomer. Following multiple administrations with alum adjuvant, the L-protein induced a strong, specific lgG antibody response, whereas the D-protein did not. This relative lack of responsiveness to the D-protein cannot be attributed to rapid excretion, since it is retained at least 4 times longer than the natural L-protein. These observations provide the first direct evidence that a folded D-amino acid protein has low immunogenicity and is long lived in vivo. Proteins with such properties may be useful as molecular platforms in a variety of chemical and pharmaco-logical applications. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340160309
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  • 7
    Electronic Resource
    Electronic Resource
    Alpha helix capping in synthetic model peptides by reciprocal side chain-main chain interactions: Evidence for an N terminal “capping box” (1994)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 18 (1994), S. 1-7 
    Details
    ISSN: 0887-3585
    Keywords: α-helix capping ; α-helix initiation ; α-helix termination ; synthetic peptides ; protein folding ; circular dichroism ; 1H nmr ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A significant fraction of the amino acids in proteins are alpha helical in conformation. Alpha helices in globular proteins are short, with an average length of about twelve residues, so that residues at the ends of helices make up an important fraction of all helical residues. In the middle of a helix, H-bonds connect the NH and CO groups of each residue to partners four residues along the chain. At the ends of a helix, the H-bond potential of the main chain remains unfulfilled, and helix capping interactions involving bonds from polar side chains to the NH or CO of the backbone have been proposed and detected. In a study of synthetic helical peptides, we have found that the sequence Ser-Glu-Asp-Glu stabilizes the alpha helix in a series of helical peptides with consensus sequences. Following the report by Harper and Rose, which identifies SerXaaXaaGlu as a member of a class of common motifs at the N termini of alpha helices in proteins that they refer to as “capping boxes,” we have reexamined the side chain-main chain interactions in a varient sequence using 1H NMR, and find that the postulated reciprocal side chain-backbone bonding between the first Ser and last Glu side chains and their peptide NH partners can be resolved: Deletion of two residues N terminal to the Ser-Glu-Asp-Glu sequence in these peptides has no effect on the initiation of helical structure, as defined by two-dimensional (2D) NMR experiments on this variant. Thus the capping box sequence Ser-Glu-Asp-Glu inhibits N terminal fraying of the N terminus of alpha helix in these peptides, and shows the side chain-main chain interactions proposed by Harper and Rose. It thus acts as a helix initiating signal. Since normal a helix cannot propagate beyond the N terminus of this structure, the box acts as a termination signal in this direction as well. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340180103
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  • 8
    Electronic Resource
    Electronic Resource
    Luminol dependent chemiluminescence and thiol group oxidation provoked by neutrophils is attributable to different oxidizing species (1987)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 1 (1987), S. 165-171 
    Details
    ISSN: 0884-3996
    Keywords: Polymorphonuclear leukocytes (PMNL) ; oxidation ; thiol groups ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Luminol-dependent chemiluminescence and thiol group oxidation of glutathione and human serum albumin were measured in order to demonstrate whether the inhibition of polymorphonuclear leukocyte chemiluminescence by albumin was attributable to thiol group oxidation. We have shown that: 1thiol groups on glutathione and albumin are oxidized by PMNL stimulated by soluble and phagocytic stimuli;2thiol group oxidation in albumin and glutathione did not correlate with the inhibitory effects of these substances on luminol-dependent chemiluminescence with respect to time course, magnitude, effects of known scavengers or extracellular activity. It was therefore concluded that thiol group oxidation was not the cause of albumin inhibition of luminol-dependent chemiluminescence;3a metastable oxidant was identified after PMNL activation which was capable of oxidizing thiol groups but unable to elicit chemiluminescence form luminol.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bio.1170010304
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  • 9
    Electronic Resource
    Electronic Resource
    The characterization of composite agarose/hydroxyethylcellulose matrices for the separation of DNA fragments using capillary electrophoresis (1997)
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 1980-1989 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; DNA restriction fragments ; Hydroxyethyl cellulose ; Agarose ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Mixtures of the polysaccharide derivatives, 19% hydroxyethylated SeaPrep agarose (SP-AG) and hydroxyethylcellulose (HEC), in aqueous buffer solutions are applied for the first time to the separation of DNA fragments using capillary electrophoresis (CE). These matrices form unique size-sieving networks that allow the separation of a wide size range of DNA fragments in a single analysis. Relative to their homogeneous counterparts, the composite separation matrices provide enhanced selectivity properties of DNA fragments, especially for fragments greater than 1000 base pairs (bp) in length. Additionally, the effects on separation performance of capillary temperature, the incorporation of a DNA intercalator, and applied field strength are demonstrated. Solution viscosity measurements of the homogeneous and composite matrix solutions were made in order to establish the entanglement threshold concentrations for the unique size-sieving solutions. The relatively low solution viscosities of the composite separation matrices allow reproducible replacement of the separation matrix between analyses. The mechanism of separation of DNA fragments for the composite matrices is proposed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150181117
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  • 10
    Electronic Resource
    Electronic Resource
    Insulin-regulatable phosphoproteins in 3T3-L1 adipocytes form detergent-insoluble complexes not associated with caveolin (1997)
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 2629-2637 
    Details
    ISSN: 0173-0835
    Keywords: Insulin action ; Glucose transporter 4 ; Protein complexes ; Two-dimensional polyacrylamide gel electrophoresis ; Protein phosphorylation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Whole body glucose homeostasis is dependent on the action of insulin. In muscle and adipose tissues, insulin stimulates glucose uptake by inducing the translocation of vesicles containing the glucose transporter GLUT4 to the cell surface. While the mechanisms of insulin-regulated GLUT4 translocation are not fully understood, some signaling intermediates have been implicated in this process. Interestingly, some of these intermediates, including IRS-1 and PI3K, have been localised to the same intracellular membrane fraction as the GLUT4 storage pool, designated here as the high-speed pellet (HSP) fraction. This raises the possibility that many of the downstream insulin signaling intermediates may be located within close proximity to intracellular GLUT4. The goal of this study was to test this hypothesis in 3T3-L1 adipocytes. A large proportion of adipocyte phosphoproteins co-fractionated in the HSP fraction. In an attempt to resolve insulin-regulatable phosphoproteins, we subjected 32P-labeled subcellular fractions to two-dimensional gel electrophoresis (2-DE). Insulin reproducibly stimulated the phosphorylation of 12 spots in the HSP fraction. Most of the HSP phosphoproteins were insoluble in the nonionic detergent Triton X-100, whereas integral membrane proteins such as GLUT4 and intracellular caveolin were soluble under the same conditions. These results suggest that insulin-regulatable phosphoproteins in adipocytes may be organized in microdomains within the cell and that this assembly may act as an efficient conductor of the signaling proteins to rapidly facilitate downstream biological responses. Further study is required to establish the molecular basis for these detergent-insoluble signaling complexes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150181419
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