Crystallization and preliminary crystallographic studies of a new L-asparaginase encoded by the Escherichia coli genome

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 P2₁2₁2₁ (unit-cell parameters a = 50.3, b = 77.6, c = 148.2 Å) and diffract to 1.65 Å 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 αβ heterodimers, where the subunits α and β are the product of autoproteolytic cleavage of the immature protein.