Related Experiment Video
Updated: Oct 1, 2026
Microcrystallography of Protein Crystals and In Cellulo Diffraction
Published on: July 21, 2017
Homo crystallographicus--quo vadis?
Gerard J Kleywegt1, T Alwyn Jones
1Department of Cell and Molecular Biology, Uppsala University, Biomedical Centre, Box 596, SE-751 24 Uppsala, Sweden. gerard@xray.bmc.uu.se
Abstract:
As macromolecular crystal structures are determined and refined in an increasingly automated fashion, careful assessment of the reliability and quality of the resulting models becomes increasingly important. Here, we analyze various issues related to the reliability and quality of macromolecular crystal structures deposited between 1991 and 2000. We find that the average resolution at which these structures are determined is essentially constant. In line with this observation, the average quality as measured by Ramachandran analysis does not improve as a function of time. On the other hand, an observed decrease of the average discrepancy between free and conventional R values suggests that the fit of model and data is improving. Finally, we present a surprising correlation between the tendency of crystallographers to deposit their experimental data and the free R values of their models.
More Related Videos
10:32Sample Preparation and Transfer Protocol for In-Vacuum Long-Wavelength Crystallography on Beamline I23 at Diamond Light Source
Published on: April 23, 2021
07:08Crystallization and In Situ Room Temperature Data Collection Using the Crystallization Facility at Harwell and Beamline VMXi, Diamond Light Source
Published on: March 8, 2024
Related Concept Videos
01:29Determination of Crystal Structures
02:18X-ray Crystallography
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
01:25Crystal Growth: Principles of Crystallization
Initiating crystallization involves manipulating the concentration of the solute and the temperature of the solution. Since crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent – the...
01:21Polymer Classification: Crystallinity
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...