Chang L H, Burkey K O, Alben J O, Marshall A G
Biochemistry. 1984 Jul 31;23(16):3659-62. doi: 10.1021/bi00311a013.
Ultraviolet (260 and 280 nm) and Fourier-transform infrared (FT-IR) spectra of Bacillus subtilis ribosomal 5S RNA have been acquired between 20 and 90 degrees C. In the presence of added Mg2+, the average UV melting midpoint, Tm, is 60 (A260) or 62 degrees C (A280), resolving into two components (Tm = 54 and 68 degrees C). In the presence of 10 mM Mg2+, the normalized A260 increases by about 5%, and the average Tm increases to 70 degrees C (A260 or A280), resolving into components at 63 and 73 degrees C at 260 nm but not resolved at 280 nm. From the difference of the 5S RNA FT-IR spectra between 90 and 30 degrees C, the number of base pairs in B. subtilis 5S RNA was determined by the procedure outlined in the accompanying paper [Li, S.-J., Burkey, K. O., Luoma, G. A., Alben, J. O., & Marshall, A. G. (1984) Biochemistry (preceding paper in this issue)]. Addition of 10 mM Mg2+ increases the number of A-U pairs by 1 (from 11 to 12) and the number of G-C pairs by 2 (from 15 to 17). FT-IR melting curve midpoints show that addition of Mg2+ increases the melting point for both A-U and G-C pairs in B. subtilis 5S RNA. The A-U pairs melt before G-C pairs (56 vs. 64 degrees C) in the absence of Mg2+, but both types of pairs melt at the same temperature (67 vs. 70 degrees C) in the presence of Mg2+.(ABSTRACT TRUNCATED AT 250 WORDS)
已在20至90摄氏度之间获取了枯草芽孢杆菌核糖体5S RNA的紫外（260和280纳米）光谱和傅里叶变换红外（FT - IR）光谱。在添加Mg2 +的情况下，平均紫外熔解中点，即解链温度（Tm），在260纳米处为60摄氏度，在280纳米处为62摄氏度，可分解为两个组分（Tm = 54和68摄氏度）。在存在10 mM Mg2 +的情况下，归一化的A260增加约5%，平均Tm增加到70摄氏度（260纳米或280纳米处），在260纳米处分解为63和73摄氏度的组分，但在280纳米处未分解。根据90至30摄氏度之间5S RNA的FT - IR光谱差异，按照随附论文[Li, S.-J., Burkey, K. O., Luoma, G. A., Alben, J. O., & Marshall, A. G. (1984) Biochemistry（本期前一篇论文）]中概述的程序确定了枯草芽孢杆菌5S RNA中的碱基对数量。添加10 mM Mg2 +会使A - U对的数量增加1个（从11个增加到12个），G - C对的数量增加2个（从15个增加到17个）。FT - IR熔解曲线中点表明，添加Mg2 +会提高枯草芽孢杆菌5S RNA中A - U对和G - C对的熔点。在不存在Mg2 +的情况下，A - U对比G - C对先熔解（56摄氏度对64摄氏度），但在存在Mg2 +的情况下，两种类型的碱基对在相同温度下熔解（67摄氏度对70摄氏度）。（摘要截断于250字）
