CRYSTALLIZATION AND PRELIMINARY-X-RAY STUDIES OF WILD-TYPE AND CATALYTIC-SITE MUTANT ALPHA-AMYLASE FROM BACILLUS-SUBTILIS

Recombinant α-amylase (EC3.2.1.1) from Bacillus subtilis has been crystallized by the hanging drop vapor diffusion method using polyethylene glycol as precipitant. Crystals of wild-type protein diffract to at least 2.2 Å resolution, and belong to the space group P212121 with a = 72.2 Å, b = 74.9 Å, c = 116.1 Å with probably one molecule in the asymmetric unit. A catalytic-site mutant created by site-directed mutagenesis has also been grown as isomorphous crystals with a = 72.6 Å, b = 74.4 Å, c = 116.7 Å. Structural studies of both wild-type and mutant proteins will provide a basis for understanding the catalytic mechanism of α-amylase. © 1993 Academic Press Limited.