title: Shake-and-Bake applications using simulated reference-beam data for crambin.
abstract: The Shake-and-Bake method, as implemented in the computer program SnB, has been applied to simulated reference-beam data for the small protein crambin at several resolutions in the range 1.5-3.0 A. Sets of triplet invariants were generated having simulated mean triplet-phase errors from 0 to 60 degrees. Provided that these errors were no larger than 40 degrees, it was possible (at all resolutions tested) to find trial sets of individual Bragg phases with mean errors of 40-45 degrees. At 1.5 A, this could be achieved using only a single reference-beam data set. Peak picking provided useful phase constraints even at the lowest resolution tested. These results suggest that direct methods may be useful in conjunction with reference-beam data at resolutions lower than 1.2 A.
authors.affiliation: Hauptman-Woodward Medical Research Institute, Buffalo, NY 14203, USA. weeks@hwi.buffalo.edu
authors.forename: C M
authors.initials: CM
authors.lastname: Weeks
authors.forename: H
authors.initials: H
authors.lastname: Xu
authors.forename: H A
authors.initials: HA
authors.lastname: Hauptman
authors.forename: Q
authors.initials: Q
authors.lastname: Shen
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D007090:Image Interpretation, Computer-Assisted; D010940:Plant Proteins / Q000737:chemistry*
chemical_list: D010940:Plant Proteins; C024934:crambin protein, Crambe abyssinica