【摘要】 (一)我们进行了DNA,大分子RNA及sRNA在加酸变性过程中“融点”及融化曲线改变的比较,当pH下降时三种核酸的融点都逐渐下降,大分子RNA与sRNA的融化曲线类似,而与DNA的不同。(二)经过加酸变性再恢复中性时,大分子RNA及sRNA的“融点”与融化曲线皆恢复较好,DNA则不能完全恢复。(三)根据DNA在加酸变性后再恢复中性时的融化曲线看,可以认为DNA在加酸变性后两链并未完全解开,可能留有“核心”部分。此核心部分“融点”高,估计含有大量的鸟便嘌呤-胞嘧啶链。另外在融化曲线中部有明显的热稳定区存在。(四)由DNA的加酸变性及加热变性后再恢复中性的融化曲线特征比较,两者极为相似,说明此两种变性作用所造成的结果是一致的。(五)由sRNA在加酸变性过程中融点与融化曲线的特征看来,所有变化皆与大分子RNA一致,而不与DNA一致,说明sRNA在溶液中的结构与大分子RNA相似而与DNA不同。更多还原

【Abstract】 (1)"Melting points" (T_m) of calf thymus deoxyribonucleic a(?)id (DNA), rat liver high-molecular weight ribonucleic acid (HRNA) and soluble ribonucleic acid (sRNA)from E. coli during acid denaturation were studied. On decreasing the pH, all the T_m of the three kinds of nucleic acids are lowered and the shapes of the melting curves of HRNA and sRNA. are similar, but they are different from that of the DNA.(2)On reneutralization after acid denaturation of the nucleic acids, the T_m of HRNA and sRNA restore essentially to the original values but that of the DNA is not.(3)The melting curves of the neutralized DNA after acid denaturation shows that hydrogen bonds do not completely broken on acid denaturation, and a "core" is left which shows higher T_m. In addition, in melting curves of DNA there are heat stable regions around 60°C.(4)Since the melting curves of neutralized DNA after acid denaturation are very similar with that of the quickly cold DNA sample from thermal denaturation, it is probable that the same process takes place during the two kinds of denaturation.(5)The characters of T_m and melting curves of sRNA during acid denaturation obviously show that the secondary structure of sRNA in solution is similar to HRNA but not to DNA.更多还原