title: Crystallization and preliminary crystallographic studies of a new crystal form of Escherichia coli L--asparaginase II (Ser58Ala mutant).
abstract: Periplasmic Escherichia coli L-asparaginase II with an Ser58Ala mutation in the active-site cavity has been crystallized in a new orthorhombic form (space group P2(1)2(1)2). Crystals of this polymorph suitable for X-ray diffraction have been obtained by vapour diffusion using two sets of conditions: (i) 1% agarose gel using MPD as precipitant (pH 4.8) and (ii) liquid droplets using PEG-MME 550 (pH 9.0). The crystals grown in agarose gel are characterized by unit-cell parameters a = 226.9, b = 128.4, c = 61.9 A and diffract to 2.3 A resolution. The asymmetric unit contains six protein molecules arranged into one pseudo-222-symmetric homotetramer and an active-site competent dimer from which another homotetramer is generated by crystallographic symmetry.
authors.affiliation: Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Poznañ, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Kozak
authors.forename: M
authors.initials: M
authors.lastname: Jaskólski
mesh_terms: D000409:Alanine; D019943:Amino Acid Substitution; D001215:Asparaginase / Q000737:chemistry* / Q000302:isolation & purification; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D012694:Serine
chemical_list: D012694:Serine; D001215:Asparaginase; D000409:Alanine