Related Experiment Video
Updated: Jun 26, 2026
10:10
Neutron Crystallography Data Collection and Processing for Modelling Hydrogen Atoms in Protein Structures
Published on: December 1, 2020
Model-building strategies for low-resolution X-ray crystallographic data.
Anjum M Karmali1, Tom L Blundell, Nicholas Furnham
1Department of Biochemistry, University of Cambridge, Cambridge, England.
Acta Crystallographica. Section D, Biological Crystallography
|January 28, 2009
Summary
Interpreting low-resolution X-ray crystallographic data is difficult due to ambiguous electron-density maps. This review covers strategies and automation for improving macromolecular structure determination from challenging data.
Area of Science:
- Structural Biology
- Biophysics
- Crystallography
Background:
- Low-resolution X-ray crystallographic data present significant interpretation challenges, including ambiguous electron-density maps.
- These challenges complicate main-chain tracing and side-chain assignment in macromolecular structure determination.
- The increasing number of biologically important structures solved at resolutions poorer than 3.5 Å necessitates improved interpretation methods.
Purpose of the Study:
- To review the challenges associated with interpreting low-resolution X-ray crystallographic data.
- To discuss strategies developed to overcome these interpretation difficulties.
- To explore advancements in automating the process of macromolecular model generation.
Main Methods:
- Review of existing literature on low-resolution X-ray crystallography.
- Analysis of strategies for electron-density map interpretation.
- Consideration of model generation techniques from electron microscopy data.
Main Results:
- Identified key challenges in electron-density map interpretation at low resolutions.
- Summarized various strategies employed to improve model building.
- Highlighted the potential of automation and complementary methods like electron microscopy.
Conclusions:
- Despite difficulties, low-resolution crystallography yields important structural insights.
- Advanced interpretation strategies and automation are crucial for progress.
- Electron microscopy offers parallel approaches for high-confidence model generation.
Related Concept Videos
01:29Determination of Crystal Structures
In the late 1800s, the revelation that light extended beyond visible wavelengths led to the discovery of X-rays by Wilhelm Roentgen. Recognized as high-energy electromagnetic radiation with short wavelengths, X-rays prompted exploration into their interaction with crystals. Max von Laue proposed in 1912 that the periodic arrangement of atoms, ions, or molecules in crystals would cause them to diffract X-rays, a hypothesis confirmed through experiments with copper sulfate and zinc sulfide...
02:18X-ray Crystallography
The size of the unit cell and the arrangement of atoms in a crystal may be determined from measurements of the diffraction of X-rays by the crystal, termed X-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...
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...
01:10X-ray Diffraction of Biological Samples
X-ray diffraction or XRD is an analytical tool that utilizes X-rays to study ordered structures such as crystalline organic and inorganic samples, polycrystalline materials, proteins, carbohydrates, and drugs.
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...