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Related Concept Videos

Determination of Crystal Structures01:29

Determination 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...
Crystal Field Theory - Octahedral Complexes02:58

Crystal Field Theory - Octahedral Complexes

Crystal Field Theory
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...
Crystal Field Theory - Tetrahedral and Square Planar Complexes02:46

Crystal Field Theory - Tetrahedral and Square Planar Complexes

Tetrahedral 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,...
Imperfections in Crystal Structure: Stoichiometric Point Defects01:26

Imperfections in Crystal Structure: Stoichiometric Point Defects

Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...
Imperfections in Crystal Structure: Non-Stoichiometric Defects01:29

Imperfections in Crystal Structure: Non-Stoichiometric Defects

Non-stoichiometric defects refer to a type of defect in the crystal structure of a compound where the ratio of its constituent elements deviates from the ideal stoichiometric ratio. There are two main types of non-stoichiometric defects: metal excess defects and metal deficiency defects.Metal excess defects occur when there is a slight surplus of metal ions than what is required by the stoichiometric ratio of the compound. For example, heating a sodium chloride crystal in sodium vapor results...
X-ray Crystallography02:18

X-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...

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Heterogeneity and dynamics in villin headpiece crystal structures.

Jianmin Meng1, Christopher James McKnight

  • 1Boston University School of Medicine, USA.

Acta Crystallographica. Section D, Biological Crystallography
|April 25, 2009
PubMed
Summary

Structural analysis of the villin headpiece domain (HP67) reveals significant protein dynamics and heterogeneity. Different crystal structures show variations, with one closely resembling NMR data, highlighting inherent protein flexibility.

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Published on: May 13, 2020

Area of Science:

  • Biochemistry
  • Structural Biology
  • Biophysics

Background:

  • The villin headpiece domain (HP67) is crucial for F-actin binding and bundling in brush-border microvilli.
  • Previous studies have determined HP67's NMR and crystal structures.
  • Understanding protein structure-function relationships requires detailed structural insights.

Purpose of the Study:

  • To present new crystal structures of HP67 and its mutant (H41Y) in a different crystal form.
  • To investigate structural variations and dynamics between different crystal forms and with NMR data.
  • To explore the inherent flexibility of small proteins like HP67.

Main Methods:

  • X-ray crystallography to determine new crystal structures of HP67 and H41Y.
  • Comparison of new crystal structures with previously determined structures and NMR data.
  • Analysis of B-factor profiles to infer harmonic motions and dynamics.

Main Results:

  • Two distinct molecules (Mol A and Mol B) were found in the asymmetric unit of the new crystal form (space group P6(1)).
  • Mol A is similar to a previously determined structure (Mol X), while Mol B shows significant deviations, particularly in the N-terminal subdomain.
  • Mol B, the most structurally different, is closer to the averaged NMR structure, suggesting lattice contacts are not the primary cause of deviation.
  • Harmonic motions differ between crystal structures, with those in the same space group showing similar patterns.

Conclusions:

  • Different crystal structures of villin headpiece (HP67) exhibit significant heterogeneity and dynamics.
  • Protein flexibility is evident even in small proteins, influencing their crystal packing and structural representation.
  • The study underscores the importance of considering multiple structural states when interpreting protein structure-function relationships.