title: Ionic effects on the structure of nucleoprotein cores from adenovirus.
abstract: Nucleoprotein cores, prepared from adenovirus type 5 with a deoxycholate/heat treatment, consist of the viral DNA and two major internal proteins. The core particles exhibit structural characteristics that are highly reproducible and dependent on their ionic environment. In low-ionic-strength buffer, the cores had a sedimentation coefficient of 180 S and appeared in the electron microscope as homogeneous particles with distinct centers from which numerous arms and loops radiated. Condensation of the cores was induced by Mg2+ or Ca2+ over the range 0 to 1 mM. The sedimentation coefficient increased monotonically with divalent cation concentration, reaching a maximum of 405 S in 1 mM Mg2+. A corresponding condensation in the core structure was observed by electron microscopy. Increasing concentrations of NaCl also produced a conformational change in the cores, with an almost linear increase in sedimentation velocity up to 274 S in 0.04 M NaCl. Between 0.05 and 1.0 M NaCl, the cores were insoluble. In 2.0 M NaCl, the cores were again soluble with an s20,w of 228 S. Under all ionic strength conditions in which the cores were soluble, both core proteins remained bound to the DNA.
mesh_terms: D000260:Adenoviruses, Human / Q000378:metabolism*; D002122:Calcium Chloride; D002413:Cations, Divalent; D006801:Humans; D007624:KB Cells; D008274:Magnesium; D015636:Magnesium Chloride; D008854:Microscopy, Electron; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D009698:Nucleoproteins / Q000302:isolation & purification / Q000378:metabolism*; D009994:Osmolar Concentration; D011487:Protein Conformation; D012965:Sodium Chloride
chemical_list: D002413:Cations, Divalent; D009698:Nucleoproteins; D015636:Magnesium Chloride; D012965:Sodium Chloride; D008274:Magnesium; D002122:Calcium Chloride