title: Urea and guanidine hydrochloride induced dissociation and denaturation of bacteriophage F2 capsid.
abstract: A single, low molecular weight protein is found after urea or guanidine hydrochloride (Gdn.HCl) treatment of empty capsids derived from bacteriophage f2. The final product of denaturation is apparently a monomer, existing as a random coil in larger than or equal to 4.0 M Gdn.HCl but in a less extended form in 8.0 M urea. In contrast, an 11 S protein component is isolated after treatment of the intact virus with 4.0 M Gdn.HCl (Zelazo & Haschemeyer, 1969), indicating that RNA plays a role in stabilizing larger subunits. Denaturation by Gdn.HCl occurs in two stages as measured by changes in CD and Stokes radius: dissociation that involves a structural perturbation of aromatic side chains, followed by a major, cooperative transition that evidently results in the loss of all noncovalent structure. Denaturation by urea appears to be a much less cooperative process that occurs in several steps over a wide range of urea concentration (1--7 M). In both urea and Gdn.HCl, dissociation into subunits begins at a lower concentration of denaturant than the major changes in conformation.
mesh_terms: D001435:Bacteriophages / Q000187:drug effects*; D002213:Capsid; D002850:Chromatography, Gel; D002942:Circular Dichroism; D006146:Guanidines / Q000494:pharmacology*; D008970:Molecular Weight; D011489:Protein Denaturation; D014508:Urea / Q000494:pharmacology*; D014764:Viral Proteins
chemical_list: D006146:Guanidines; D014764:Viral Proteins; D014508:Urea