CRYSTALLIZATION AND PRELIMINARY-X-RAY CRYSTALLOGRAPHIC STUDIES OF THERMOSTABLE XYLANASE CRYSTALS ISOLATED FROM PAECILOMYCES-VARIOTI

A highly thermostable xylanase isolated from the thermophilic fungus P aecilomyces varioti has been crystallized by the vapour diffusion meth od. The isolation of this enzyme by crystallization directly from the culture filtrate projects this fungus as an important source for large -scale production of pure xylanase. The crystals belong to orthorhombi c space group P2(1)2(1)2(1) with the unit cell dimensions a = 38.48 An gstrom, b = 53.87 Angstrom and c = 90.23 Angstrom. Four molecules occu py a volume of 187,039.4 Angstrom(3) along with 34% of solvent. The da ta collected with an area detector to the resolution of 2.7 Angstrom w ere used to calculate the unit cell parameters and Matthews' constant. The optical behaviour of the crystal was studied at different tempera tures to understand its thermal stability