title: Conformational states of chromatin nu bodies induced by urea.
abstract: Monomer chromatin nu bodies (nu1) from chicken erythrocyte nuclei were exposed to 0-10 M urea plus 0.2 mM EDTA (PH 7). Alterations in nu1 conformation were examined using hydrodynamic methods (i.e., S, eta, and (formula: see text)), thermal denaturation, circular dichroism, reactivity of histone thiol groups to N-ethyl maleimide, and electron microscopy. The two domains of a nu body (i.e., the DNA-rich shell and the protein-rich core) aeared to respond differently to the destabilizing effects of increasing urea; DNA conformation and stability exhibited noncooperative changes; the core protein structure revealed cooperative destabilization between 4 and 7 M urea. Companion studies on the conformation of the inner histone "heterotypic tetramer" also revealed cooperative destabilization with increasing urea concentration.
mesh_terms: D000818:Animals; D002645:Chickens; D002843:Chromatin; D002942:Circular Dichroism; D004247:DNA; D004912:Erythrocytes; D005033:Ethylmaleimide; D006657:Histones; D006358:Hot Temperature; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation / Q000187:drug effects; D009691:Nucleic Acid Denaturation; D014508:Urea / Q000494:pharmacology
chemical_list: D002843:Chromatin; D006657:Histones; D014508:Urea; D004247:DNA; D005033:Ethylmaleimide