title: On the variability of experimental data in macromolecular crystallography.
abstract: Experimental errors as determined by data-processing algorithms in macromolecular crystallography are compared with the direct error estimates obtained by a multiple crystal data-collection protocol. It is found that several-fold error inflation is necessary to account for crystal-to-crystal variation. It is shown that similar error inflation is observed for data collected from multiple sections of the same crystal, indicating non-uniform crystal growth as one of the likely sources of additional data variation. Other potential sources of error inflation include differential X-ray absorption for different reflections and variation of unit-cell parameters. The underestimation of the experimental errors is more severe in lower resolution shells and for reflections characterized by a higher signal-to-noise ratio. These observations partially account for the gap between the expected and the observed R values in macromolecular crystallography.
authors.affiliation: Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, USA. epozhars@rx.umaryland.edu
authors.forename: Edwin
authors.initials: E
authors.lastname: Pozharski
mesh_terms: D000465:Algorithms; D000818:Animals; D002645:Chickens; D018360:Crystallography, X-Ray / Q000379:methods*; D050556:Fatty Acid-Binding Proteins / Q000032:analysis; D006801:Humans; D006836:Hydro-Lyases / Q000032:analysis; D009113:Muramidase / Q000032:analysis; D020124:Thermotoga maritima
chemical_list: C493410:FABP4 protein, human; D050556:Fatty Acid-Binding Proteins; D009113:Muramidase; D006836:Hydro-Lyases; C020671:glycerol dehydratase