Initial evaluation of a direct detection device detector for single particle cryo-electron microscopy

We report on initial results of using a new direct detection device (DDD) for single particle reconstruction of vitreous ice embedded specimens. Images were acquired on a Tecnai F20 at 200 key and a nominal magnification of 29,000x. This camera has a significantly improved signal to noise ratio and modulation transfer function (MTF) at 200 key compared to a standard CCD camera installed on the same microscope. Control of the DDD has been integrated into Leginon, an automated data collection system. Using GroEL as a test specimen, we obtained images of similar to 30 K particles with the CCD and the DDD from the same specimen sample using essentially identical imaging conditions. Comparison of the maps reconstructed from the CCD images and the DDD images demonstrates the improved performance of the DDD. We also obtained a 3D reconstruction from similar to 70 K GroEL particles acquired using the DOD; the quality of the density map demonstrates the potential of this new recording device for cryoEM data acquisition. (C) 2011 Elsevier Inc. All rights reserved.