title: Distribution of intercalative dye binding sites in chromatin.
abstract: Actinomycin D (AMD) and ethidium bromide (EB) were found to bind to chromatin isolated from a variety of gander tissues according to a strong and weak process analogous to that found for deproteinized DNA. Distribution of the dye intercalation sites in chromatin and DNA were evaluated at low r-values (dye bound per nucleotide) by following the appearance of free dye released from chromatin and DNA during thermal denaturation. The AMD dissociation profiles closely resembled the DNA or chromatin-DNA denaturation profiles; whereas the EB derivative dissociation profiles, indicated 3 major transitions for transcriptionally active chromatin with the main component corresponding to the single component which characterizes DNA. The DNA-like component was greatly reduced for mature erythrocyte chromatin but could be generated by removal of histone I and V. Removal of residual non acid-soluble proteins from dehistonized chromatin, urea treatment or dissociation and reconstitution of chromatin favoured conversion to the DNA-like component with loss of the other two. This study indicates that more than one type of binding exists generally in chromatin.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002843:Chromatin / Q000187:drug effects / Q000378:metabolism*; D004396:Coloring Agents / Q000378:metabolism*; D003609:Dactinomycin / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism; D004996:Ethidium / Q000378:metabolism*; D005777:Geese; D006358:Hot Temperature; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008297:Male; D009691:Nucleic Acid Denaturation; D009928:Organ Specificity; D009994:Osmolar Concentration; D013053:Spectrophotometry; D014508:Urea / Q000494:pharmacology
chemical_list: D002843:Chromatin; D004396:Coloring Agents; D003609:Dactinomycin; D014508:Urea; D004996:Ethidium