ESTIMATION OF VARIANCE DISTRIBUTION IN 3-DIMENSIONAL RECONSTRUCTION .2. APPLICATIONS

A previously developed theory of three-dimensional (3-D) variance esti mation [J. Opt. Soc. Am. A 12, 2615-2627 (1995)] is applied to the str uctural study of a hemocyanin-Fab complex with the electron microscope . precise locations of structurally variable regions of the macromolec ule are determined from the 3-D variance maps. The structural differen ces among different classes of the macromolecular complex are assessed by the use of the statistical t-test, and the 3-D antibody binding si tes are revealed. is demonstrated for visually identifying a 3-D confo rmational change by the inspection of the 3-D variance map. Our analys is lays the foundation for numerous practical applications of variance estimation in the 3-D imaging of macromolecules. (C) 1995 Optical Soc iety of America