Forum 11/06/2003

“A Graphical Representation of Data Quality for Three-Dimensional Structure Analysis of Two-Dimensional Crystals”

Anchi Cheng, Research Associate – Department of Cell Biology, The Scripps Research Institute, La Jolla, CA

Electron crystallography of two-dimensional (2D) crystals is a powerful approach for the analysis of membrane protein structure.  3D structures are derived by merging data from 2D crystals at varying tilt axis and tilt angle.  I will present a graphical representation that incorporates the tilt geometry to display the quality of each image. Information that can be extracted from the plot includes a symbol for each image that reflects the completeness of the data for that crystal.   The polar plot also includes a novel parameter that reflects the minimal variation in tilt axis to ensure overlap of data points in reciprocal space between images at the same tilt angle.  I have found it especially useful for tracking the progress of data collection in processing images from tilted crystals and for assessing the completeness of two data sets prior to determination of difference maps.

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