SnB: Applying Shake-and-Bake to Proteins

The Shake-and-Bake algorithm is a powerful formulation of direct methods which alternates reciprocal-space phase refinement with filtering in real space to impose constraints. As implemented in SnB version 1.5, the current distributed version of the computer program, Shake-and-Bake combines peak picking in real space with optimization via either parameter-shift reduction of the minimal-function value or tangent-formula refinement. The procedure employs a multisolution approach in which initial trial structures consist of randomly positioned atoms. The SnB program has provided ab initio solutions for protein structures containing as many as 600 independent non-H atoms, provided that goodquality diffraction data are available to 1.1Å resolution.