Cross-correlation and merging of crystallographic reflections derived from cryoelectron micrographs of 3D crystals: application to the Limulus acrosomal bundle

J Struct Biol. 2003 Oct-Nov;144(1-2):195-208. doi: 10.1016/j.jsb.2003.09.024.


A method is described for merging in reciprocal space of electron microscopic data from three-dimensional crystals of the acrosomal bundle. Permutation of indices was required to find the proper alignment of data from different bundles. The method utilizes a statistical evaluation of the significance of the cross-correlation results to indicate the proper order for merging. The three-dimensional (3D) merging is a reference-free operation that does not depend on choosing a "zero-tilt" user-defined starting point. Results from the merging are given and the merged 3D data to 9.5A resolution is evaluated for coherence. General issues such as statistical significance of cross-correlation function peaks, symmetry evaluation, and phase coherence as a function of amplitude are discussed.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acrosome / metabolism*
  • Algorithms
  • Animals
  • Biophysics / methods*
  • Cryoelectron Microscopy / methods*
  • Crystallography, X-Ray / methods*
  • Horseshoe Crabs / metabolism*
  • Image Processing, Computer-Assisted
  • Imaging, Three-Dimensional
  • Male