Resolution

From Proteopedia

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Resolution is an average value for the uncertainty of atomic positions in a crystallographic model. High values for resolution (e.g. 5.0 Å) mean high uncertainty, and low values (e.g. 1.0 Å) mean much less uncertainty. 2.05 Å is the median resolution for X-ray crystallographic results in the Protein Data Bank (43,066 on May 2, 2008).

The uncertainty for each atom is quantitated in its temperature value.

The images at right show how the electron density map^[1] becomes more accurate and detailed as the uncertainty (resolution value) decreases from 5.0 Å to 0.5 Å.

The images at right were taken from a Movie^[2].

See Also

• R value
• Free R
• Believe It or Not

Websites

• Resolution at ProteinExplorer.Org's Glossary.

• Resolution vs. Electron Density Maps.

• A Glossary of Terms from Crystallography, NMR, and Homology Modeling

Notes

1. ↑ These are "perfect" electron density maps calculated from the atomic model (R factor = 0.0%, perfect phases and amplitudes, contoured at 1 sigma). Electron density maps based on experimental data would fit the true conformation less well. Because these electron density maps were calculated from an atomic model that lacked hydrogen atoms, the electron densities for hydrogen atoms that would appear with experimental data at a resolution of 0.5 Å do not appear.
2. ↑ The movie (Image:Resolution holton.mpeg) was created by James Holton at the Advanced Light Source of the Berkeley Laboratory at the University of California. Holton gave explicit permission to use this movie in Proteopedia. The original source was http://ucxray.berkeley.edu/~jamesh/movies.