title: [Nuclear ribonucleoproteins containing messenger RNA. 12. Fluorescence studies of the secondary structure of pre-mRNA in nuclear RNP-particles].
abstract: Secondary structure of pre-mRNA in nuclear ribonucleoprotein particles (30S-particles) was examined using fluorescent dyes: acridine orange, acriflavine and ethidium bromide. Comparison of ethidium bromide and acriflavine adsorption isotherms for RNP-particles and free RNA and a study of acridine orange dimerization on binding to RNP revealed that 70% of pre-mRNA in 30S-particles is accessible for the dye binding. Dye molecules were adsorbed on double-stranded sequences (11--12% of the total amount of RNA in 30S-particles) and on the single-stranded parts of RNA (58--59% of 30S-particles), the rest part of RNA was unaccessible for the dye binding. A method involving measurements of acriflavine fluorescence quantum yields was used for the determination of nucleotide composition of double-stranded parts of RNA in the 30S-particles. AU-nucleotide content thus obtained was approximately 50%, as was established also for free pre-mRNA. Na+ ions weaken the interaction between the protein and pre-mRNA in 30S particles and increase mobility of double-stranded parts of this nucleic acid.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000032:analysis; D008433:Mathematics; D009690:Nucleic Acid Conformation; D009698:Nucleoproteins; D011485:Protein Binding; D012333:RNA, Messenger; D051381:Rats; D012261:Ribonucleoproteins; D012964:Sodium; D013050:Spectrometry, Fluorescence
chemical_list: D009698:Nucleoproteins; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D012964:Sodium
vernacular_title: Iadernye ribonukleoproteidy, soderzhashchie informatsionnuiu RNK. 12. Izuchenie vtorichnoĭ struktury pro-mRNK v sostave iadernykh RNP-chastits fluorestsentnymi metodami.