title: Partial melting of the segment around pseudouridine in yeast 5S RNA.
abstract: Pseudouridine in yeast 5S RNA was modified with 4-bromomethyl-7-methoxy-coumarin(BMC). Temperature dependence of fluorescence intensity was measured at various concentrations of Mg2+ and K+ cations. Hyperchromicity was also measured. At 100mM KCl and 10mM Mg2+, fluorescence intensity decreased with temperature as free BMC except a plateau at 45 degrees C. Withdrawal of Mg2+ from the buffer resulted in a large quenching at 20 degrees C and showed a gradual increase of fluorescence intensity with temperature, indicating a partial melting of the segment around pseudouridine. The temperature range agrees with the low melting temperature shown by hyperchromicity. In 10 mM KCl solution, the effects are more exaggerated.
mesh_terms: D007700:Kinetics; D008274:Magnesium; D009691:Nucleic Acid Denaturation; D011188:Potassium; D011560:Pseudouridine / Q000032:analysis*; D012331:RNA, Fungal / Q000302:isolation & purification*; D012335:RNA, Ribosomal / Q000302:isolation & purification*; D012441:Saccharomyces cerevisiae / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D014468:Umbelliferones; D014529:Uridine / Q000031:analogs & derivatives*
chemical_list: D012331:RNA, Fungal; D012335:RNA, Ribosomal; D014468:Umbelliferones; D011560:Pseudouridine; C000317:4-bromomethyl-7-methoxycoumarin; D008274:Magnesium; D011188:Potassium; D014529:Uridine