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  • Theoretical, Physical and Computational Chemistry  (2)
  • adjusting of energy functions  (1)
  • 1
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 25 (1996), S. 379-388 
    ISSN: 0887-3585
    Schlagwort(e): protein modeling ; lattice approximation error ; adjusting of energy functions ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Lattice models of proteins can approximate off-lattice structures to arbitrary precision with RMS (root mean squared) deviations roughly equal to half the lattice spacing (Rykunov et al., Proteins 22:100-109, 1995; Reva et al., J. Comp. Biol., 1996). However, even small distortions in the positions of chain links lead to significant errors in lattice-based energy calculations (Reva et al., J. Comp. Chem., 1996). These errors arise mainly from rigid interactions (such as steric repulsion) which change their energies considerably at a range which is much smaller than the usual accuracy of lattice modeling (〉1.0 Å). To reduce this error, we suggest a procedure of adjusting energy functions to a given lattice. The general approach is illustrated with energy calculations based on pairwise potentials by Kolinski et al. (J. Chem. Phys. 98:1-14, 1993). At all the lattice spacings, from 0.5-3.8 Å, the lattice-adjusted potentials improve the accuracy of lattice-based energy calculations and Increase the correlations between off-lattice and lattice energies. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 17 (1996), S. 1025-1032 
    ISSN: 0192-8651
    Schlagwort(e): Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Informatik
    Notizen: Energy calculations based on lattice models of protein chains are always approximate, because any such a model distorts distances between chain links and, consequently, the energies of interaction between them. The energetic errors of lattice models are examined here for 15 proteins of different sizes and types of secondary structure, for lattice spacings ranging from 0.25 to 2.5 Å. The lattice models are derived using previously described algorithms which insure a minimal root mean square (rms) deviation from the off-lattice structure for any given lattice-protein orientation. For each protein structure we computed a set of different lattice models with virtually equal rms deviations, and then compared their energies. Energy calculations were based on the pairwise potentials. We found that the energies of lattice models follows a normal distribution with a nonnegligible dispersion, even at a fine lattice spacing of 0.25 Å. For any lattice model of a protein, the lattice spacing must be 1.0 Å or less in order to be able to distinguish energetically between the folded and extended states. However, when an ensemble of lattice models is considered, this distinction can be made for lattice spacing up to 2.0 Å. We conclude that to attain a better approximation of the protein lattice model energies, one must adjust potentials to the lattice spacing. © 1996 by John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 1639-1662 
    ISSN: 0192-8651
    Schlagwort(e): automated docking ; binding affinity ; drug design ; genetic algorithm ; flexible small molecule protein interaction ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Informatik
    Notizen: A novel and robust automated docking method that predicts the bound conformations of flexible ligands to macromolecular targets has been developed and tested, in combination with a new scoring function that estimates the free energy change upon binding. Interestingly, this method applies a Lamarckian model of genetics, in which environmental adaptations of an individual's phenotype are reverse transcribed into its genotype and become heritable traits (sic). We consider three search methods, Monte Carlo simulated annealing, a traditional genetic algorithm, and the Lamarckian genetic algorithm, and compare their performance in dockings of seven protein-ligand test systems having known three-dimensional structure. We show that both the traditional and Lamarckian genetic algorithms can handle ligands with more degrees of freedom than the simulated annealing method used in earlier versions of AUTODOCK, and that the Lamarckian genetic algorithm is the most efficient, reliable, and successful of the three. The empirical free energy function was calibrated using a set of 30 structurally known protein-ligand complexes with experimentally determined binding constants. Linear regression analysis of the observed binding constants in terms of a wide variety of structure-derived molecular properties was performed. The final model had a residual standard error of 9.11 kJ mol-1 (2.177 kcal mol-1) and was chosen as the new energy function. The new search methods and empirical free energy function are available in AUTODOCK, version 3.0.   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 1639-1662, 1998
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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