This unit is the first in a series of four units covering the analysis of nucleic acid structure by molecular modeling. This unit provides an overview of computer simulation of nucleic acids. Topics include the static structure model, computational graphics and energy models, generation of an initial model, and characterization of the overall three-dimensional structure.
Subject GroupNucleic Acid Chemistry; Nucleic Acid Structure and Folding; Structural Analysis of Biomolecules; Experimental Determination of Structure; Folding and Conformational Change Molecular modeling, loosely defined, relates to the use of models to investigate the threedimensional structure, dynamics, energetics, and properties of a molecule or set of molecules. At the heart of this is specification of a molecular model, which provides a molecular structure at an appropriate level of granularity, usually in terms of threedimensional atomic coordinates. Molecular modeling can be approached on many levels, ranging from energy minimization (finding the set of coordinates that minimizes the energy) with a complete ab-initio quantum-mechanical treatment of the energetics, to sampling "reasonable" conformations with a simplified energy representation or potential, to physically manipulatable models where no implicit energy representation is included. These methods serve not only as tools to aid in the interpretation of experimental data, but to directly complement such data by providing a relationship between the macroscopic behaviors observed experimentally and the microscopic properties represented in the model or simulation.As discussed in other units, various molecular modeling tools can serve as conformational search engines for sampling conformational space subject to the restraints inferred from nuclear magnetic resonance (NMR; see UNIT 7.2) and crystallography (see UNIT 7.1 and UNIT 7.6) experiments. This is a critical step in the refinement of three-dimensional atomic structure. Inclusion of some representation of the energy, such as through the use of a specially parameterized empirical force field, can aid in this endeavor by limiting sampling to more realistic (in terms of energy) conformations.Correspondence to: Thomas E. Cheatham, III, tec3@utah.edu.
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Author ManuscriptCurr Protoc Nucleic Acid Chem. Author manuscript; available in PMC 2014 May 21.
Published in final edited form as:Curr Protoc Nucleic Acid Chem. 2001 November ; 0 7: Unit-7.5. doi:10.1002/0471142700.nc0705s06.
NIH-PA Author ManuscriptNIH-PA Author Manuscript
NIH-PA Author ManuscriptAs mentioned above, molecular mechanics methods (described in greater detail in UNIT 7.8) can be used not only as a tool in structure refinement, but can directly complement experimental data. For instance, molecular dynamics simulations can be used to aid in the interpretation of NMR order parameters, or to estimate anisotropic rotational diffusion. In addition, computer simulation techniques have the potential to give structural and dynamic insight into the atomic ...