Screening and optimizing crystallization conditions for a new protein can take as little as 3-6 weeks, though some samples may take longer. Please note that the process is substantially accelerated if the protein is found in our FastLane™ libraries. The libraries contain 600+ proteins ready for crystallization (Premium list) or for expression, purification, and crystallization according to verified protocols (Standard list). However, even when the protein’s structure is known from previous studies, it is often necessary to perform new screening experiments to obtain high-quality crystals. Slight changes in expression, purification, or characterization protocols, or the presence of new additives in the buffer, such as ligands for co-crystallization to obtain a protein-ligand complex, may also require modifications to the crystallization conditions. In addition, some experiments, such as crystallographic fragment screening, require hundreds of stable crystals with well-reproducible crystallization conditions. We initially run hundreds of screens using commercial sparse-matrix screens such as those available at Hampton Research. We routinely use high-throughput, high-precision liquid-handling robotics for the initial screens and during subsequent optimization of newly identified crystallization conditions. Typically, approximately 5 mg of protein at a concentration of around 10 mg/ml is required at the initial stage. Lower protein concentrations can be used if solubility is an issue. Posible temperature effects are tested using temperature screening that typically starts at 4°C and 20°C as initial reference points.
