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  • 1
    Electronic Resource
    Electronic Resource
    Genetic and biochemical analysis of in vivo protein folding and subunit assembly (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 125-129 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The in vivo pathway of folding and subunit assembly of a trimeric bacteriophage protein has been studied by characterizing precursors to the native protein and by analyzing temperature-sensitive mutations that kinetically block the pathway. The native trimer is formed via an intermediate composed of three partially folded chains, the protrimer. At 39°C, temperature-sensitive mutations prevent the formation of both the native trimer and the protrimer, possibly by destabilizing earlier intermediates. However, the mutations do not affect the stability of the native protein, formed at 30°C. Thus, these mutations identify amino acid residues involved in interactions that determine the folding pathway.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220120
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular thermodynamic model for Helix-Helix docking and protein aggregation (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1015-1024 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The formation of aggregates, rather than correctly folded polypeptide chains, is a pressing problem in biotechnology that has been difficult to approach quantitatively. The competition between folding and aggregation has been carefully analyzed for bovine growth hormone (bGH) and can be attributed to incorrect helix-helix docking for this four-helix bundle protein. An extended molecular thermodynamic model reported here represents Gibbs energy changes associated with intramolecular and intermolecular helix-helix dockings occurring during protein folding and protein aggregation. The model incorporates (1) a semiempirical local composition Gibbs energy expression to account for the helix-helix hydrophobic interactions, which favor helix-helix docking and aggregation and (2) a Flory-Huggins-type Gibbs energy expression to describe the configurational entropy of the polypeptide backbone conformation, which favors disaggregation. For the folding and aggregation of bGH, the molecular thermodynamic model provides estimates for the Gibbs energies and thermodynamic stabilities of various conformations of bGH and qualitatively accounts for the competition between aggregation and productive folding. It also successfully describes the inhibition of aggregation found with peptides corresponding to bGH helical sequences and the effect of site-directed mutagenesis.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410433
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  • 3
    Electronic Resource
    Electronic Resource
    Bidirectional chiral inversion of the enantiomers of the nonsteroidal antiinflammatory drug oxindanac in dogs (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 460-466 
    Details
    ISSN: 0899-0042
    Keywords: chiral inversion ; oxindanac ; dogs ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nonsteroidal antiinflammatory drug oxindanac exists as two enantiomers, with most of its pharmacological activity residing in the (S)-isomer. The behavior of its enantiomers was investigated in dogs. Bidirectional inversion occurred in heparinised plasma and blood, with a ratio of enantiomers [S:R] of 7.3:1 being achieved at equilibrium after incubation for 24 h at 37°C. There was no detectable inversion of either isomer in plasma incubated at 4°C for up to 8 h or in aqueous solution at 37°C for up to 36 h. Bidirectional inversion also occurred in vivo, with a ratio of plasma AUC (0 ∞)s [S:R] of 8.1:1. The ratio of enantiomers reached equilibrium within 2 hr following (S)- or rac-oxindanac, and within 8 h following (R)-oxindanac. Elimination t½s of the isomers were the same (R, 12.1 h, S, 13.3 h). There were no differences in the ratio of enantiomers following oral or intravenous application, suggesting that a systemic site for inversion was predominant. Although concentrations of the respective isomers were similar at equilibrium following administration of either (R)-, (S)-, or rac-oxindanac, AUC (0 ∞)s differed due to the delay in reaching equilibrium. The extent of inversion to the (S)-isomer was 100, 73.2, and 60.7% after administration of (S)-, rac-, and (R)-oxindanac, respectively. Although pharmacological activity might be equivalent at equilibrium following administration of either (R)-, (S)-, or rac-oxindanac; efficacy at early time points should be superior in the order (S) 〉 racemate 〉 (R). In conclusion both enantiomers of oxindanac undergo conversion to their respective antipodes in dogs, although the inversion of R to S is more efficient than that of S to R. This bidirectional inversion occurred in vivo, and in vitro in plasma and blood. © 1994 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530060603
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  • 4
    Electronic Resource
    Electronic Resource
    A molecular thermodynamic approach to predict the secondary structure of homopolypeptides in aqueous systems (1992)
    New York : Wiley-Blackwell
    Biopolymers 32 (1992), S. 1375-1392 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Under physiological conditions, many polypeptide chains spontaneously fold into discrete and tightly packed three-dimensional structures. The folded polypeptide chain conformation is believed to represent a minimum Gibbs energy of the system, governed by the weak interactions that operate between the amino acid residues and between the residues and the solvent.A semiempirical molecular thermodynamic model is proposed to represent the Gibbs energy of folding of aqueous homopolypeptide systems. The model takes into consideration both the entropy contribution and the enthalpy contribution of folding homopolypeptide chains in aqueous solutions. The entropy contribution is derived from the Flory-Huggins expression for the entropy of mixing. It accounts for the entropy loss in folding a random-coiled polypeptide chain into a specific polypeptide conformation. The enthalpy contribution is derived from a molecular segment-based Non-Random Two Liquid (NRTL) local composition model [H. Renon and J. M. Prausnitz (1968) AIChE J., Vol. 14, pp. 135-142; C.-C. Chen and L. B. Evans (1986) AIChE J., Vol. 32, pp. 444-454], which takes into consideration of the residue-residue, residue-solvent, and solvent-solvent binary physical interactions along with the local compositions of amino acid residues in aqueous homo-polypeptides. The UNIFAC group contribution method [A. Fredenslund, R. L. Jones, and J. M. Prausnitz (1975) AIChE J., 21, 1086-1099; A. Fredenslund, J. Gmehling, and P. Rasmussen (1977) Vapor-Liquid Equilibrium Using UNIFAC, Elsevier Scientific Publishing Company, Amsterdam], developed originally to estimate the excess Gibbs energy of solutions of small molecules, was used to estimate the NRTL binary interaction parameters.The model yields a hydrophobicity scale for the 20 amino acid side chains, which compares favorably with established scales [Y. Nozaki and C. Tanford (1971) Journal of Biological Chemistry, Vol. 46, pp. 2211-2217; E. B. Leodidis and T. A. Hatton (1990) Journal of Physical Chemistry, Vol. 94, pp. 6411-6420]. In addition, the model generates qualitatively correct thermodynamic constants and it accurately predicts thermodynamically favorable folding of a number of aqueous homopolypeptides from random-coiled states into α-helices. The model further facilitates estimation of the Zimm-Bragg helix growth parameter s and the nucleation parameter s for amino acid residues [B. H. Zimm and J. K. Bragg (1959) Journal of Chemical Physics, Vol. 31, pp. 526-535]. The calculated values of the two parameters fall into the ranges suggested by Zimm and Bragg. © 1992 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360321011
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  • 5
    Electronic Resource
    Electronic Resource
    Polymerization mechanism of polypeptide chain aggregation (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 54 (1997), S. 333-343 
    Details
    ISSN: 0006-3592
    Keywords: aggregation ; folding intermediates ; inclusion body ; polymerization ; protein folding ; protein-protein interactions ; self-assembly ; P22 tailspike protein ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The misfolding of polypeptide chains and aggregation into the insoluble inclusion body state is a serious problem for biotechnology and biomedical research. Developing a rational strategy to control aggregation requires understanding the mechanism of polymerization. We investigated the in vitro aggregation of P22 tailspike polypeptide chains by classical light scattering, nondenaturing gel electrophoresis, two-dimensional polyacrylamide gel electrophoresis (PAGE), and computer simulations. The aggregation of polypeptide chains during refolding occurred by multimeric polymerization, in which two multimers of any size could associate to form a larger aggregate and did not require a sequential addition of monomeric subunits. The cluster-cluster polymerization mechanism of aggregation is an important determinant in the kinetic competition between productive folding and inclusion body formation. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 333-343, 1997.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    P22 morphogenesis I: Catalytic scaffolding protein in capsid assembly (1974)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 2 (1974), S. 202-224 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: About 250 molecules of the 42,000 molecular weight gene 8 product catalyze the polymerization of the major phage coat protein into a precursor shell temporarily containing both proteins. The resulting prohead appears to be a shell structure with the P8, or scaffolding protein, on the inside, and the coat protein on the outside. In concert with DNA condensation inside the shell, all 250 scaffolding molecules exit from the prohead, without proteolytic cleavage. These molecules then recycle and catalyze the formation of more proheads from newly synthesized coat protein. Such proteins, which catalyze assembly by temporarily associating with an intermediate stage, may represent a general mechanism of macromolecular assembly.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400020215
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  • 7
    Electronic Resource
    Electronic Resource
    Assembly of the tail of bacteriophage T4 (1975)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 3 (1975), S. 24-38 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The protein products of at least 21 phage genes are needed for the formation of the tail of bacteriophage T4. Cells infected with amber mutants defective in these genes are blocked in the assembly process. By characterizing the intermediate structures and unassembled proteins accumulating in mutant-infected cells, we have been able to delineate most of the gene-controlled steps in tail assembly. Both the organized structures and unassembled proteins serve as precursors for in vitro tail assembly.We review here studies on the initiation, polymerization, and termination of the tail tube and contractile sheath and the genetic control of these processes. These studies make clear the importance of the baseplate; if baseplate formation is blocked (by mutation) the tube and sheath subunits remain essentially unaggregated, in the form of soluble subunits.Seventeen of the 21 tail genes specify proteins involved in baseplate assembly. The genes map contiguously in two separate clusters, one of nine genes and the other of eight genes. Recent studies show that the hexagonal baseplate is the end-product of two independent subassembly pathways. The proteins of the first gene cluster interact to form a structure which probably represents one-sixth of the outer radius. The products of the other gene cluster interact to form the central part of the baseplate.Most of the phage tail precursor proteins appear to be synthesized in a non-aggregating form; they are converted to a reactive form upon incorporation into preformed substrate complexes, without proteolytic cleavage. Thus reactive sites are limited to growing structures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400030104
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