Multi-wavelength anomalous dispersion

Multi-wavelength anomalous diffraction (sometimes Multi-wavelength anomalous dispersion; abbreviated MAD) is a technique used in X-ray crystallography that facilitates the determination of the three-dimensional structure of biological macromolecules (e.g. DNA, drug receptors) via solution of the phase problem. This method doesn't need two crystal structures (one native and one with heavy atom) for a unique phase solution. Instead anomalous diffraction is recorded at different wavelengths of coherent X-ray light at a synchrotron facility.

MAD was developed by Wayne Hendrickson while working as a postdoctoral researcher under Jerome Karle at the United States Naval Research Laboratory. The mathematics upon which MAD (and progenitor Single wavelength anomalous dispersion) were based were developed by Jerome Karle, work for which he was awarded the 1985 Nobel Prize in Chemistry (along with Herbert Hauptman).

See also

Anomalous Dispersion

• Multi-wavelength Anomalous Dispersion (MAD)
• Single wavelength anomalous dispersion (SAD)

Isomorphous Replacement

Two methods for providing the needed phasing information by introducing heavy atoms into isomorphous crystals:

• Multiple isomorphous replacement (MIR); and
• Single isomorphous replacement with anomalous signal (SIRAS)

Other

• Patterson map

External links

• MAD phasing — an in depth tutorial with examples, illustrations, and references.
• HHMI Bio for Wayne Hendrickson
• Wayne Hendrickson Home Page
• Hendrickson Laboratory Summary of Research
• Jerome Karl Nobel Biography
• NRL Recognition of Nobel Prize

Computer programs

• The SSRL Absorption Package —
• CHOOCH —
• Shake-and-Bake (SnB) —
• SHELX —