Cross-correlation and merging of crystallographic reflections derived from cryoelectron micrographs of 3D crystals: application to the Limulus acrosomal bundle.
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.
Schmid
Michael F
MF
Verna and Marrs McLean Department of Biochemistry and Molecular Biology and National Center for Macromolecular Imaging, Baylor College of Medicine, Houston, TX 77030, USA. mschmid@bcm.tmc.edu
D000177:Acrosome / Q000378:metabolism*; D000465:Algorithms; D000818:Animals; D001703:Biophysics / Q000379:methods*; D020285:Cryoelectron Microscopy / Q000379:methods*; D018360:Crystallography, X-Ray / Q000379:methods*; D006737:Horseshoe Crabs / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male