Macromolecular Crystallography Protocols

Volume 364 of the series Methods in Molecular Biology™ pp 255-272

Quality Control and Validation

  • Gerard J. KleywegtAffiliated withDepartment of Cell and Molecular Biology, Uppsala University, Biomedical Center

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This chapter discusses two important aspects of the structure determination process that are related to the accuracy and reliability of the crystallographic model under investigation. Quality control is defined as the analysis of an intermediate model to identify aspects of it that are unusual in some sense and that could, therefore, be a result of errors in the model building or refinement process. Any such errors need to be fixed, if at all possible, prior to analysis and publication of the model. Validation is the process of assessing the reliability of the final model (or certain aspects of it, e.g., the active site residues) that is about to be analyzed, published, deposited, and possibly used in follow-up studies.

Key Words

Electron density model bias model building protein structure quality control Ramachandran plot refinement structure validation X-ray crystallography