title: Preparation, crystallization and preliminary X-ray crystallographic studies of diadenosine tetraphosphate hydrolase from Shigella flexneri 2a.
abstract: Diadenosine tetraphosphate (Ap4A) hydrolase (EC 3.6.1.41) hydrolyzes Ap4A symmetrically in prokaryotes. It plays a potential role in organisms by regulating the concentration of Ap4A in vivo. To date, no three-dimensional structures of proteins with significant sequence homology to this protein have been determined. The 31.3 kDa Ap4A hydrolase from Shigella flexneri 2a has been cloned, expressed and purified using an Escherichia coli expression system. Crystals of Ap4A hydrolase have been obtained by the hanging-drop technique at 291 K using PEG 550 MME as precipitant. Ap4A hydrolase crystals diffract X-rays to 3.26 A and belong to space group P2(1), with unit-cell parameters a = 118.9, b = 54.6, c = 128.5 A, beta = 95.7 degrees.
authors.affiliation: Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.
authors.forename: Wenxin
authors.initials: W
authors.lastname: Hu
authors.forename: Qihai
authors.initials: Q
authors.lastname: Wang
authors.forename: Ruchang
authors.initials: R
authors.lastname: Bi
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000737:chemistry* / Q000235:genetics; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray / Q000379:methods*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D012763:Shigella flexneri / Q000201:enzymology*
chemical_list: D011994:Recombinant Proteins; D017766:Acid Anhydride Hydrolases; C020023:bis(5'-nucleosyl)tetraphosphatase (asymmetrical)