Chitinase is necessary for fungal growth and cell division and, therefore, is an ideal target for the design of inhibitors which may act as antifungal agents. A chitinase from the fungal pathogen Coccidioides immitis has been expressed as a fusion protein with gluathione-S-transferase (GST), which aids in purification. After cleavage from GST, chitinase was crystallized from 30% PEG 4000 in 0.1 M sodium acetate pH 4.6. The crystals have a tetragonal crystal lattice and belong to space group P4(1)2(1)2 or P4(3)2(1)2 and diffract to 2.2 Angstrom resolution. The unit-cell parameters are a = b = 91.2, c = 95.4 Angstrom; there is only one chitinase molecule in the asymmetric unit.National Institutes of Health GM 30048National Science Foundation MCB-9601096Foundation for ResearchWelch FoundationMolecular Bioscience