Purification, crystallization and preliminary X‐ray diffraction analysis of the Trichoderma reesei hydrophobin HFBI

Hydrophobins are fungal proteins that are capable of altering the hydrophobicity of surfaces by self‐assembly at hydrophilic–hydrophobic interfaces. Here, the growth of hydrophobin crystals suitable for X‐ray crystallography is reported. The hydrophobin HFBI from Trichoderma reesei was crystallized by vapour diffusion in hanging drops in 30% PEG 4000, 0.1  M sodium citrate pH 4.3 buffer containing 0.2  M ammonium acetate and CYMAL‐5 detergent (initial concentration of 2.4 m M ). HFBI crystals are hexagonal and belong to space group P 6 1 (or P 6 5 ), with unit‐cell parameters a  =  b  = 45.9, c = 307.2 Å. The HFBI used in the crystallization experiments was purified from fungal cell walls.