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  • 11
    Electronic Resource
    Electronic Resource
    Modification of polyolefin surfaces with iron cluster oxidants (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 389-396 
    Details
    ISSN: 0887-624X
    Keywords: polyethylene ; polypropylene ; oxidation ; biodegradation ; C—H bond activation ; functionalization ; XPS ; ATR-IR ; surface ; Gif ; oxidase ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modification of polyethylene and polypropylene film and powder surfaces with oxygen and hydrogen peroxide is promoted by nonporphyrinic, nonfree radical based iron reagents such as Fe3O(OCOCH3)6(C6H5N)3.5 and FeCl3 • 6H2O/picolinic acid. These oxidation systems introduced small amounts of carbonyl groups onto the surface of these hydrocarbon polymers. The most visible manifestation of this reaction was increased polyolefin wettability toward water. IR spectroscopy, XPS spectroscopy, and chemical derivatization all were used to verify that the reaction had occurred and that a chemically derivatizable surface had been prepared. The overall process produced a fraction of the density of functional groups introduced by conventional etching chemistry.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300306
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  • 12
    Electronic Resource
    Electronic Resource
    Amine-quinone polyurethanes. I. Preparation of polyurethane block copolymers containing 2,5-bis(N-2-hydroxyethyl-N-methylamino)-1,4-benzoquinone diol monomer (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2881-2886 
    Details
    ISSN: 0887-624X
    Keywords: polyurethanes ; benzoquinones ; amine-quinones ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The amine-quinone monomer, 2,5-bis(N-2-hydroxyethyl-N-methylamino)-1,4-benzoqui-none (AQM-1), was prepared by the multiple-step condensation of 2-(N-methylam-ino)ethanol with benzoquinone in the presence of oxygen. This crystalline monomer was used to prepare a series of amine-quinone polyurethanes by condensation polymerization, either in the melt or in solution (THF or DMF), with a diisocyanate (MDI, TDI, or IPDI) and an oligomeric diol [poly(caprolactone) or poly(1,2-butylene glycol)]. The amine-quinone functional group was stable under the polymerization conditions, and was incorporated into the main chain, giving red-brown polyurethanes that had molecular weights in the range of 11,000-90,000 and were soluble in THF, MEK, DMF, and DMSO. The thermal properties were consistent with a two-phase morphology with an amorphous soft segment, containing the oligomeric diol, and a microcrystalline hard segment, containing AQM-1. The polymers having a low hard segment content (〈50%) were rubbery (soft segment Tg 〈-25°C); polymers having a high hard segment content (〉50%) were thermoplastic (hard segment Tg〉150°C). © 1995 John Wiley & Sons, Inc.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331704
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  • 13
    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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  • 14
    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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  • 15
    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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  • 16
    Electronic Resource
    Electronic Resource
    Water-Soluble imide-amide copolymers. I. Preparation and characterization of poly [acrylamide-co-sodium N-(4-sulfophenyl) maleimide]Presented at the 72nd Canadian Chemical Conference, Victoria, British Columbia, June 4-8, 1989.Dedicated to the memory of Dr. W. M. Leung (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2949-2968 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sodium N-(4-sulfophenyl) maleimide (SPMI) and its saturated succinimide counterpart were first prepared according to established methods. Hydrolysis experiments on these monomers monitored by 1H-NMR showed that although SPMI monomer was about 15% hydrolyzed in D2O at 23°C in 24 h. Sodium N-(4-sulfophenyl) succinimide, which is similar in structure to the imide units in the copolymers, was only 1% hydrolyzed after 18 days at 23°C and 29% hydrolyzed after 18 days at 60°C. This indicated that the saturated imide rings in the copolymer might be sufficiently stable to hydrolysis for the copolymers to be useful. However, hydrolysis at high pH demonstrated that the imide rings would be rapidly saponified under alkaline conditions, destroying the structural rigidity that the intact rings might have provided in the copolymer chains. Sodium N-(4-sulfophenyl) maleimide (SPMI) was copolymerized with acrylamide in water at 30°C without cleavage of the imide ring. Water-soluble poly [acrylamide-co-sodium-N-(4-sulfophenyl) maleimide] (PAMSM) samples containing from 7.4 to 64 mol % imide were prepared. Photoacoustic FTIR and 13C-NMR spectra were used to confirm the structure of the copolymers obtained. Elemental analysis was used to determine the imide content of the copolymers, and from this composition data reactivity ratios were calculated for the two component monomers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080281106
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  • 17
    Electronic Resource
    Electronic Resource
    Water-Soluble imide-amide copolymers. II. Preparation and characterization of poly (acrylamide-co-p-maleimidobenzoic acid)Presented at the 72nd Canadian Chemical Conference, Victoria, British Columbia, June 4-8, 1989.Dedicated to the memory of W. M. Leung (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2969-2982 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The comonomer required, p-maleimidobenzoic acid (MBA) was first prepared in good yield by refinements of published methods. p-Carboxysuccinanilic acid (CSA), and p-succinimidobenzoic acid (SBA), were also prepared to provide models useful for IR and NMR for spectroscopic assignments of the new copolymers. Polymerization of MBA with acrylamide in glacial acetic acid at 60°C gave copolymers with estimated viscosity average molecular weights of 60,000 to 90,000. Yields and viscosity average molecular weights decreased as the MBA to acrylamide monomer feed ratio was increased. The rate of incorporation of MBA into the copolymer rose from 7 to 23% when the mole ratio in the feed was raised from 5 to 20%. Decreasing the initiator concentration increased molecular weights by less than predicted and reduced the yield of copolymer for any given feed ratio of MBA to acrylamide. In all cases about 30-40% of the MBA units in the purified copolymers were hydrolyzed. A change to dimethyl sulfoxide solvent gave good, and poor yields of copolymer at 5 and 10 mol % MBA, respectively, and no copolymer at 20 mol % MBA. Viscosity average molecular weights of the copolymer products prepared in DMSO were somewhat lower than obtained for the copolymers prepared in acetic acid. Polymerization in a DMSO-water mixture gave a negligible yield of polymeric product. Instead, only hydrolysates of MBA precipitated when the coloured polymerization solutions were added to methanol.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080281107
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  • 18
    Electronic Resource
    Electronic Resource
    Water-Soluble imide-amide copolymers. III. Preparation and characterization of poly (acrylamide-co-N,N-diallylaniline) and poly (acrylamide-co-sodium N,N-diallylsulfanilate)Presented at the 72nd Canadian Chemical Conference, Victoria, British Columbia, June 4-8, 1989.Dedicated to the memory of W. M. Leung (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2983-2996 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N,N-diallylaniline monomer was prepared in good yields, for use in preparation of homopolymer and for copolymerization with acrylamide. Functionalized N,N-diallylaniline monomer, as sodium N,N-diallylsulfanilate, was also prepared in good yields for copolymerization with acrylamide. Both monomers were fully characterized by elemental analysis, IR, and NMR. Poly (N,N-diallylaniline) was obtained by polymerization of a strongly acidic aqueous solution of N,N-diallylaniline initiated with hydrogen peroxide. Spectroscopic data from this homopolymer was used to facilitate spectral assignments of the new copolymers. Copolymers of acrylamide with N,N-diallylamine were prepared at monomer feed ratios of 10, 20, and 30 mol % amine and gave 3.5, 7.4, and 8.9 mol % incorporation, respectively. Similar diallyl monomer incorporation rates were obtained for the copolymerization of sodium N,N-diallylsulfanilate with acrylamide. With 10, 30, and 50 mol % of the sodium salt relative to acrylamide, 3.9, 8.4, and 19.2 mol % incorporation of the diallyl monomer was obtained.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080281108
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  • 19
    Electronic Resource
    Electronic Resource
    Solvent effects on ester alcoholysis at functionalized polyethylene surfaces (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1209-1217 
    Details
    ISSN: 0887-624X
    Keywords: polyethylene ; functionalization ; transesterification ; surface ; fluorescence ; kinetics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of solvent on the accessibility and reactivity of an ester-bound fluorophore at a functionalized polyethylene-solvent interface have been studied. Fluorophore-labeled polyethylene surfaces were prepared by blending together a small amount of a pyrene esterterminated ethylene oligomer and a host linear low density polyethylene in solution. Films cast from such solutions were then studied by fluorescence spectroscopy to show that a significant number of the entrapped pyrene groups were at the polyethylene-solvent interface and capable of reaction with soluble reagents. Subsequently, transesterification of these ester-bound pyrenes using various sodium alkoxides in alcohol, alcohol-toluene, or alcohol-tetrahydrofuran solvent mixtures was studied by fluorescence and UV-visible spectroscopic analysis of the supernatant. The extent of alcoholysis of such esters was found to be significantly affected by the solvent chosen and by the structure of the alcohol. © 1995 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330803
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  • 20
    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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