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  • 1995-1999  (9)
  • 1990-1994  (10)
  • 1980-1984  (7)
  • 1950-1954  (3)
  • 1900-1904
  • Chemistry  (29)
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 32 (1992), S. 1623-1629 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potentials of mean force (pmfs) for rotation around the X1 aromatic side-chain dihedrals of the zwitterionic bis-penicillamine enkephalin pentapeptide have been determined in both aqueous and saline solution. These side chains are known to be associated with the pharmacophore and their conformational populations are thought to be critical for activity. It is found that the association between chloride ions and the peptide in saline solution simulations has profound effects on the relative energies of the g-, g+, and t conformations, and also the barriers between them. Using the pmfs we have also calculated the respective Boltzmann-weighted 3Jαβ vicinal coupling constants. The agreement between the calculated and experimentally determined coupling constants is poor for the pmf in pure water, but substantially improved for the pmf determined in saline solution. Reasons for these differences appear to be related to the experimental conditions. © 1992 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0009-2940
    Keywords: Rhenium ; Technetium ; 8a-Amino-6-methyl-ergoline ; Chelates ; Structure elucidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Current research in radiopharmaceutical chemistry is aimed at the design of technetium-based receptor-binding radiotracers because of the excellent nuclide properties of the isotope 99mTc. Tc tracers and the corresponding complexes of rhenium, as the inactive surrogate of Tc, are required to imitate organic agonists or antagonists of the receptor. We have started studies with ergolines, which are known to be dopamine substitutes. The present report deals with the functionalization of 8α-amino-6-methyl-ergoline (2) with a 2-mercaptoacetyl group, and the subsequent synthesis of the first rhenium complex containing a pendent ergoline moiety [Re- O(SSS)(RS)] (HSSSH = HS-CH2CH2-S-CH2CH2-SH and RSH = 8a-amino-N-(2-mercaptoacetyl)-6-methyl-ergoline) (4). The molecular structure of the rhenium complex was determined by X-ray crystal structure analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 7 (1990), S. 366-377 
    ISSN: 0887-3585
    Keywords: computer modeling ; protein ; structure ; α-carbons ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A procedure for the construction of complete protein structures from only αcarbon coordinates is described. This involves building the backbone by sequential addition of Pro, Gly, or Ala residues. This main chain structure is then refined using molecular dynamics. Side chains are constructed by sequential addition of atoms with intermediate molecular dynamics refinement. For α lytic protease (a structure that is mostly β sheet) a backbone root mean square deviation (RMSD) of 0.19 Å and an overall RMSD of 1.24 Å from the crystallographic coordinates are attained. For troponin C (67% β-helix), where the coordinates are available only for the α-carbons, a backbone RMSD of 0.41 Å and an overall RMSD of 1.68 Å are attained (fits kindly provided by Dr. Michael James and Natalie Strynadka). For flavodoxin a backbone RMSD of 0.49 Å and an overall RMSD of 1.64 Å were attained.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 27 (1997), S. 227-233 
    ISSN: 0887-3585
    Keywords: peptide conformation ; ramachandran plot ; PDB search ; peptide dynamics ; BPTI ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A simple method is presented for projecting the conformation of extended secondary structure elements of peptides and proteins that extend over four Cαatoms onto a simple two-dimensional surface. A new set of two degrees of freedom is defined, a pseudo-dihedral involving four sequential Cαatoms, as well as the triple scalar product for the vectors describing the orientation of the three intervening peptide groups. The method provides a reduction in dimensionality, from the usual combination of multiple φ,ψ pairs to a single pair, yielding valuable information concerning the structure and dynamics of these important elements. The new two-dimensional surface is explored by reference to 63 selected protein crystal structures together with a comparison of model built peptides representing the common secondary structural elements. Dynamical aspects on this new surface are examined using a molecular dynamics trajectory of Basic Pancreatic Trypsin Inhibitor. © 1997 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1315-1324 
    ISSN: 0006-3592
    Keywords: static mixer ; MRC-5 ; anchorage dependent ; hepatitis A ; animal cell culture ; bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The titanium static mixer reactor, demonstrated for a variety of vaccine processes during the late 197s, was investigated for the production of attenuated hepatitis A virus antigen from anchorage-dependent MRC-5 cells. This reactor system used Charles River Biotechnological Services cabinets for monitoring and process control. Cell inoculation protocols, using 6000-10,000 cells/cm2, resulted on over 95% attachment at both the laboratory and pilot scales. Indirect monitoring techniques using oxygen, glucose, L-serine, and L-glutamine uptake rates were indicative of cell growth prior to virus inoculation as well as environmental and/or nutrient limitations. Seven laboratory-scale (3900 cm2) runs and one pilotscale (265,000 cm2) run were conducted to investigate refeeding regiments, parallel versus perpendicular element orientation, increased element surface area per unit volume, and scale-up performance. In general, lysate antigen yields achieved were similar to those of parallel T-flasks cultivated under similar conditions. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 520-528 
    ISSN: 0006-3592
    Keywords: human growth hormone ; animal cell culture ; purification ; serum ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Human growth hormone (hGH) is a polypeptide with 191 amino acids and a molecular mass of 22 kilodaltons. With the aid of computer molecular simulation, an hGH analog was created by altering an hGH gene to reflect the change of one amino acid (glycine [G] 120 to arginine [R]) within the third α-helix of the hGH molecule. This hGH analog, named hGHG120R, was found to be an hGH antagonist. It may have important implications in treating human conditions in which hGH levels are abnormally high, as found in type I diabetics. Several hundred milligrams of purified hGHG120R were needed to determine the biological activity of the antagonist in animal models. A multistep downstream process was developed to purify hGHG120R from cultured mouse L cells transfected with the hGHG120R gene. The process consisted of cell clarification, salt precipitation, membrane ultrafiltration, reversed phase high performance liquid chromatography, phase separation, and lyophiliation. This work discusses the rationale for the design of the process and experimental results on the purification of hGHG120R using the process. © 1995 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 111-126 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Free radical copolymerization in high-pressure autoclave reactors is studied by developing a mathematical model. Kinetic mechanisms to describe the polymerization rate, molecular weight averages, branching frequencies, as well as copolymer composition are presented. Two phase kinetics due to polymer-monomer solubilities in the reaction mixture are taken into account. Gel formation from cross-linking reactions is also analyzed. A mixing model is developed to represent the stirring effect inside the reactor. The mathematical model is implemented as a computer program to simulate commercial autoclave reactors. PID control equations are used to maintain operation at the unstable steady state. A sensitivity study is performed on the mixing model parameters and on some of the kinetic parameters and the model is compared to rate data from commercial reactors.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0947-6539
    Keywords: copper compounds ; exchange coupling ; heterometallic compounds ; lanthanide compounds ; magnetic properties ; structure elucidation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and structural characterisation of three copper-lanthanoid complexes are reported. The compounds, of general formula [Cu3M(chp)8(NO3)(S)] [M = Gd, S = H2O in 2; M = Dy, S = H2O in 3; M = Er, S = (H2O)0.5(MeOH)0.5 in 4; chp = anion of 6-chloro-2-pyridone], are made by reaction of [Cu2(chp)4] (1) with the hydrated lanthanoid nitrate salt in methanol. Structural studies reveal the three copper atoms lie in an approximate hemisphere about a central lanthanoid atom. Magnetic studies on 2 and two further Cu-Gd complexes show ferromagnetic coupling between the 3d and 4f metals. Consideration of these results along with magnetic data previously reported for Cu-Gd compounds leads to a correlation between the magnitude of this exchange coupling and the exponential of the Cu…Gd distance. This is the first magneto-structural correlation reported for mixed d-block/f-block metal complexes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 857-883 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to get an idea of the transient and stationary behavior to be looked for in a biological macromolecular system such as an enzyme or respiratory protein in the presence of its ligands, we have studied the coupled kinetic equations applicable to a simple allosteric model, based on the concerted two-state model of Monod et al. [(1965) J. Mol. Biol. 12, 88-118]. Exact solutions of the equations are given for three special cases, and two complementary methods are developed to generate approximate solutions in the general case, always, however, with the assumption that the equations are linear due to maintenance of ligand activity at a constant level. Subject to this assumption, these approximation methods have applicability to coupled rate equations beyond those considered here. As an illustration of how the results can provide the basis for a detailed analysis of actual kinetic data on working proteins, the formalism is applied to the kinetics of binding of oxygen by hemoglobin. An important result is that although time evolution to the steady state is in principle determined by several relaxation times, the effect of cooperativity for the case considered is to establish the dominance of one of them relative to the others. This suggests that for a macromolecule with a large number of binding sites, only one, or at most a few, of the many possible relaxation times are significant for specification of cooperative kinetics. The methods developed here, which will be applied more extensively elsewhere, provide a systematics for finding these dominant relaxation times.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 810-815 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In a previous paper, a two-parameter model was described that could be used to predict the hydrogen bond enthalpy of formation between two compounds forming a single hydrogen bond. This paper describes the extension of the use of the two parameters for solvents and polymeric resins in another mathematical model that involves four terms that determine the “hydrogen bonding potential” (HBP) interaction between a resin and a given solvent. Each solvent and each resin can be assigned a donating and accepting parameter (relative to hydrogen bond formation) that combine to yield a numeric value for HBP. A negative HBP value is associated with favorable hydrogen bonding between a resin and a solvent which should correspond to a situation in which solution formation is favorable. A positive HBP value indicates unfavorable interaction which discourages solution formation. Thus, HBP becomes a predictive model of solubilities. Numerical data are presented for four resins and 26 solvents that correlate well with observed solubility behavior. Using this model, it is also possible to construct “solubility maps,” and these are also discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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