title: Lessons from ten years of crystallization experiments at the SGC.
abstract: Although protein crystallization is generally considered more art than science and remains significantly trial-and-error, large-scale data sets hold the promise of providing general learning. Observations are presented here from retrospective analyses of the strategies actively deployed for the extensive crystallization experiments at the Oxford site of the Structural Genomics Consortium (SGC), where comprehensive annotations by SGC scientists were recorded on a customized database infrastructure. The results point to the importance of using redundancy in crystallizing conditions, specifically by varying the mixing ratios of protein sample and precipitant, as well as incubation temperatures. No meaningful difference in performance could be identified between the four most widely used sparse-matrix screens, judged by the yield of crystals leading to deposited structures; this suggests that in general any comparison of screens will be meaningless without extensive cross-testing. Where protein sample is limiting, exploring more conditions has a higher likelihood of being informative by yielding hits than does redundancy of either mixing ratio or temperature. Finally, on the logistical question of how long experiments should be stored, 98% of all crystals that led to deposited structures appeared within 30 days. Overall, these analyses serve as practical guidelines for the design of initial screening experiments for new crystallization targets.
authors.affiliation: Structural Genomics Consortium, University of Oxford, Roosevelt Drive, Oxford OX3 7DQ, England.
authors.forename: Jia Tsing
authors.initials: JT
authors.lastname: Ng
authors.affiliation: Center for Proteomic Chemistry, Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland.
authors.forename: Carien
authors.initials: C
authors.lastname: Dekker
authors.affiliation: Swissci AG, Industriestrasse 3, CH-6345 Neuheim, Switzerland.
authors.forename: Paul
authors.initials: P
authors.lastname: Reardon
authors.affiliation: Structural Genomics Consortium, University of Oxford, Roosevelt Drive, Oxford OX3 7DQ, England.
authors.forename: Frank
authors.initials: F
authors.lastname: von Delft
mesh_terms: D003460:Crystallization / Q000379:methods; D018360:Crystallography, X-Ray; D006801:Humans; D011506:Proteins / Q000737:chemistry*
chemical_list: D011506:Proteins
keywords: crystallization screening strategy; data mining; large-scale data sets; redundancy of conditions; sparse-matrix screens