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nanotimes Research


Electron Microscope // A 3-D Image of an Individual Protein


© Based on Material by LBL / Sabin Russell


12-01 :: January 2012


A 3-D images from a single particle (A) a series of images of an ApoA-1 protein particle, taken from different angles as indicated. A succession of four computer enhancements (projections) clarifies the signal. In the right column is the 3-D image compiled from the clarified data. B) is a close-up of the reconstructed 3-D image. C) Analysis shows how the parti- cle structure is formed by three ApoA-1 proteins (red, green, blue noodle-like models) © LBL


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esearcher Gang Ren and his colleague Lei Zhang at Lawrence Berkeley National Laboratory


(Berkeley Lab) are reporting the first 3-D images of an individual protein ever obtained with enough cla- rity to determine its structure. Scientists routinely cre- ate models of proteins using X-ray diffraction, nuclear magnetic resonance, and conventional cryo-electron microscope (cryoEM) imaging. But these models re- quire computer “averaging” of data from analysis of


thousands, or even millions of like molecules, becau- se it is so difficult to resolve the features of a single particle. Ren and Zhang have done just that, gene- rating detailed models using electron microscopic images of a single protein with a technique called “individual-particle electron tomography,” or IPET. The 3-D images reported in a research paper include those of a single IgG antibody and apolipo- protein A-1 (ApoA-1), a protein involved in human


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