title: A redetermination of the structure of the triple mutant (K53,56,120M) of phospholipase A2 at 1.6 A resolution using sulfur-SAS at 1.54 A wavelength.
abstract: The crystal structure of the triple mutant K53,56,120M of bovine pancreatic phospholipase A(2) has been redetermined using sulfur single-wavelength anomalous scattering. The synchrotron data were collected at lambda = 1.54 A and the crystal diffracted to 1.6 A resolution. The program SOLVE was used to locate the heavy atoms and to estimate the initial phases and the resulting map was then subjected to RESOLVE. The output of 455 non-H atoms, including 12 S atoms, one calcium ion and one chloride ion, were then subjected to ARP/wARP followed by REFMAC. With the improved phases, the automatic model building successfully built more than 85% of the 123 residues, excluding the N- and C-terminal residues. The final crystallographic R factor is 17.7% (R(free) = 21.7%). The refined model consists of 954 non-H protein atoms, 165 water O atoms, three 2-methyl-2,4-pentanediol (MPD) molecules, one calcium ion and one chloride ion. The present work is yet another example that shows the utility of single-wavelength anomalous scattering data for solving a protein structure.
authors.affiliation: Bioinformatics Centre, Indian Institute of Science, Bangalore 560 012, India. sekar@physics.iisc.ernet.in
authors.forename: K
authors.initials: K
authors.lastname: Sekar
authors.forename: V
authors.initials: V
authors.lastname: Rajakannan
authors.forename: D
authors.initials: D
authors.lastname: Velmurugan
authors.forename: T
authors.initials: T
authors.lastname: Yamane
authors.forename: R
authors.initials: R
authors.lastname: Thirumurugan
authors.forename: M
authors.initials: M
authors.lastname: Dauter
authors.forename: Z
authors.initials: Z
authors.lastname: Dauter
mesh_terms: D000818:Animals; D002417:Cattle; D002712:Chlorides / Q000737:chemistry; D018360:Crystallography, X-Ray; D006018:Glycols; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D010179:Pancreas / Q000201:enzymology; D010741:Phospholipases A / Q000737:chemistry* / Q000235:genetics*; D054467:Phospholipases A2; D012542:Scattering, Radiation; D013455:Sulfur / Q000737:chemistry; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D002712:Chlorides; D006018:Glycols; D014867:Water; D013455:Sulfur; D010741:Phospholipases A; D054467:Phospholipases A2; C011480:hexylene glycol