title: Diffraction studies of the particles of two closteroviruses: heracleum latent virus and heracleum virus 6.
abstract: X-ray diffraction from oriented specimens of purified preparations of particles of heracleum latent closterovirus (HLV) showed that they have a helical arrangement of protein subunits, and that the structure repeats in five helical turns in which there are 5q +/- 1 protein subunits, where q is an integer. The pitch of the helix was estimated to be 3.26 (+/- 0.10) nm. Optical diffraction patterns from electron micrographs of HLV particles give an estimated pitch of 3.3 (+/- 0.2) nm and show that the number of subunits in the repeat period is 5q-1, where q has a value of 8 or 9. Optical diffraction from electron micrographs of particles of a second closterovirus, heracleum virus 6, shows that they too have a helical structure which repeats in five turns, in which there are 5q +/- 1 protein subunits. The estimated pitch of the primary helix is 3.6 (+/- 0.2) nm, and the estimate of q is 9.
authors.affiliation: Department of Applied Physics and Electronic and Manufacturing Engineering, University of Dundee, U.K.
authors.forename: P
authors.initials: P
authors.lastname: Tollin
authors.forename: H R
authors.initials: HR
authors.lastname: Wilson
authors.forename: I M
authors.initials: IM
authors.lastname: Roberts
authors.forename: A F
authors.initials: AF
authors.lastname: Murant
mesh_terms: D008854:Microscopy, Electron; D010942:Plant Viruses / Q000648:ultrastructure*; D010944:Plants / Q000382:microbiology; D017365:Spices / Q000382:microbiology; D014771:Virion / Q000648:ultrastructure*; D014961:X-Ray Diffraction