title: Melting of local ordered structures in yeast 5S ribosomal RNA in aqueous salts.
abstract: Equilibrium and kinetics of thermal melting of yeast 5S ribosomal RNA in aqueous NaCl with or without Mg2+ were investigated by differential thermal melting and temperature jump methods. Two peaks (1 and 2) and a shoulder were observed in each of melting curves at ionic strength I=0.002-0.5 and linearity between each of melting temperatures T1m and T2m and log I was found at I=0.01-0.5 in the Mg2+-free solution. The local structures were found to be stabilized considerably by Mg2+. The temperature jump measurements gave the kinetic melting curve of the structure 1 at I=0.03 without Mg2+ or with 0.5 mM Mg2+. The kinetic Tm coincided well with the corresponding static Tm. For the structure 1, various parameters were calculated from the kinetic data, which indicated a double helical character of the structure 1. In terms of the values of Tm, G-C content, and enthalpy change of the transition of the structure 1 or 2, appropriateness of each of the secondary structure models of eukaryotic 5S RNA proposed previously was discussed.
mesh_terms: D006358:Hot Temperature; D007700:Kinetics; D008274:Magnesium; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D009994:Osmolar Concentration; D012335:RNA, Ribosomal; D012441:Saccharomyces cerevisiae; D012965:Sodium Chloride
chemical_list: D012335:RNA, Ribosomal; D012965:Sodium Chloride; D008274:Magnesium