Crystallization and preliminary X-ray analysis of the major endoglucanase from Thermoascus aurantiacus.

The major endoglucanase (35 kDa) from the thermophilic fungus Thermoascus aurantiacus has been purified from culture filtrates using an affinity method and the sequence for 35 N-terminal amino acids determined. This has allowed assignment of the enzyme to subtype A6 of family 5 endoglucanases. The enzyme has been crystallized as thick plates by the hanging-drop method using ammonium sulfate as precipitant. The crystals belong to space group P2(1)2(1)2(1) with cell edges a = 76.4, b = 85.7 and c = 89.5 A, with two molecules in the asymmetric unit, and diffract to 1.62 A resolution using synchrotron radiation. The structure will be solved by isomorphous replacement.