Jolly SAD

Examples of phasing macromolecular crystal structures based on single-wavelength anomalous dispersion (SAD) show that this approach is more powerful and may have more general application in structural biology than was anticipated. Better data-collection facilities and cryogenic techniques, coupled with powerful programs for data processing, phasing, density modification and automatic model building, means that the SAD approach may gain wide popularity owing to its simplicity, less stringent wavelength requirements and faster data collection and phasing than the multi-wavelength (MAD) approach. It can be performed at any wavelength where anomalous scattering can be observed, in many cases using laboratory X-ray sources.