STUDIES ON ALFALFA MOSAIC VIRUS .2. STRUCTURE OF VIRUS COMPONENTS

Alfalfa mosaic virus (AMV) consists of 5 components with sedimentation coefficients of 99 S, 88 S, 76 S, 68 S, and 53 S. The nucleic acid contents of the various components were found to be very similar (17.8%). Bottom and topa components had molecular weights of 7.28 × 106 and 3.85 × 106, respectively. The sizes of particles of the various components were determined from electron micrographs of AMV preparations in various negative stains. Measurements of the diameter of the particles (18 mμ) were made from electron micrographs of AMV precipitated by MgCl2. Optical diffraction patterns from electron micrographs of particles gave information from which a model series, based on an icosahedron cut across its 3-fold axis and with hexamers added to form the tubular portion, is proposed. The model series fitted the data on the components of AMV and is discussed in relation to the nucleic acid components of AMV and some of the unusual properties of the virus. © 1969.