Crystallization and preliminary crystallographic studies of a newL-asparaginase encoded by theEscherichia coligenome

A new Escherichia coli L-asparaginase belonging to the class of Ntn amidohydrolases has been crystallized using the vapour-diffusion method and PEG 4000 as the precipitant. The crystals belong to the orthorhombic space group P2(1)2(1)2(1) (unit-cell parameters a = 50. 3, b = 77.6, c = 148.2 A) and diffract to 1.65 A resolution. The structure has been solved by molecular replacement using aspartylglucosaminidase from Flavobacterium meningosepticum as the search model. The asymmetric unit contains four protein chains composed into a dimer of alphabeta heterodimers, where the subunits alpha and beta are the product of autoproteolytic cleavage of the immature protein.