A rational protocol for the successful crystallization of l ‐amino‐acid oxidase from Bothrops atrox

Despite the valuable contributions of robotics and high‐throughput approaches to protein crystallization, the role of an experienced crystallographer in the evaluation and rationalization of a crystallization process is still crucial to obtaining crystals suitable for X‐ray diffraction measurements. In this work, the difficult task of crystallizing the flavoenzyme l ‐amino‐acid oxidase purified from Bothrops atrox snake venom was overcome by the development of a protocol that first required the identification of a non‐amorphous precipitate as a promising crystallization condition followed by the implementation of a methodology that combined crystallization in the presence of oil and seeding techniques. Crystals were obtained and a complete data set was collected to 2.3 Å resolution. The crystals belonged to space group P 2 1 , with unit‐cell parameters a = 73.64, b = 123.92, c = 105.08 Å, β = 96.03°. There were four protein subunits in the asymmetric unit, which gave a Matthews coefficient V M of 2.12 Å 3  Da −1 , corresponding to 42% solvent content. The structure has been solved by molecular‐replacement techniques.