Examination of the LeafScan 45, a line-illuminating micro-densitometer, for its use in electron crystallography

A line-illuminating micro-densitometer, Scitex LeafScan 45 (LeafScan), equipped with a linear charge-coupled device (CCD) array has been examined for its use in digitization of electron micrographs for electron crystallographic studies. Until recently, electron micrographs have been routinely digitized using a point-illuminating flat-bed micro-densitometers, such as the Perkin-Elmer 1010 GM PDS micro-densitometer (PDS), which requires several hours for a single scan over an area of a few square centimeters. Here the phases extracted by processing a set of digitized images of two-dimensional (2D) bacteriorhodopsin (bR) crystals by both scanners are compared. While LeafScan yields a little better IQ values and phase data of comparable quality to those obtained by PDS, the scanning time is reduced by a factor of almost 20. Projection maps of bR crystal at 3.0 إ resolution calculated from the phases extracted from the set of images digitized either with LeafScan or PDS display no significant differences.