Encyclopedia of Chemistry

Multi-wavelength anomalous dispersion (sometimes Multi-wavelength anomalous diffraction; abbreviated MAD) is a technique used in X-ray crystallography that facilitates the determination of protein structures by allowing the solution of the phase problem. It uses X-rays of different wavelengths, relieving crystallographers from having to make several different metal-containing crystals.

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)

References

• Walsh MA, Evans G, Sanishvili R, Dementieva I, Joachimiak A (1999). MAD data collection - current trends. Acta Cryst, D55:1726-1732. doi:10.1107/S0907444999008392
• Hendrickson W, Ogata C (1997). Phase determination from multiwavelength anomalous diffraction measurements. Meth Enzymol, 276:494-523.