title: On the conformation of serine-specific transfer RNA. Studies by small-angle X-ray scattering and ultraviolet absorption of the molecule in solution.
abstract: The scattered X-ray intensities from dilute solutions of tRNASer (yeast) in 0.1 M Soerensen buffer at pH 7.0 were measured at 25 degrees C. The radius of gyration, molecular weight and volume were determined. A model equivalent in scattering is given. The change of the conformation of tRNASer by heating was followed by small-angle X-ray measurements and ultraviolet absorption in a temperature range 20-70 degrees C. The molecule begins to unfold at about 40 degrees C and 70 degrees C has a random coil conformation. Addition of magnesium stabilizes the tRNASer molecule. The reversibility of the melting process was also studied by both methods. An interesting effect was found by ultraviolet absorption: by heating the tRNASer solutions to 55 degrees C and 60 degrees C and subsequently slowly cooling, the melting curves lie at higher absorption values than the corresponding cooling curves. The small-angle data and optical properties of tRNASer are compared with those of tRNAPhe which has already been thoroughly investigated.
mesh_terms: D001665:Binding Sites; D008274:Magnesium; D008961:Models, Structural; D009690:Nucleic Acid Conformation; D012343:RNA, Transfer; D012441:Saccharomyces cerevisiae; D012694:Serine; D013056:Spectrophotometry, Ultraviolet; D014961:X-Ray Diffraction
chemical_list: D012694:Serine; D012343:RNA, Transfer; D008274:Magnesium