Maturation of MAD phasing for the determination of macromolecular structures

The method of multiwavelength anomalous diffraction (MAD) is having a large and ever-increasing impact in macromolecular crystallography. Synchrotron radiation is essential for the practical implementation of this concept for solving crystal structures, but the method was slow to evolve despite two decades of synchrotron availability. Other factors critical in the maturation of MAD analyses have included the development of area detectors for the accurate and rapid recording of diffraction patterns, techniques for cryopreservation against radiation damage, the systematic incorporation of selenomethionine into recombinant proteins, and new beamlines equipped for optimized MAD experiments. Continued expansion of MAD applications is anticipated since several new beamlines designed to accommodate MAD experiments have recently become operational.