二价金属离子对鲑鱼精DNA热稳定性的影响

The effects of Mg 2+, Ca 2+, Mn 2+, Co 2+ and Ni 2+ on the thermal stability of Salmon Sperm DNA were investigated by employing differential scanning calorimetry method. For the divalent cations, the shielding effect plays the dominant role in the interaction of nucleic acid chains when they are in low concentrations, as reflected in the moderate increasing of DNA melting temperature. Along with increasing concentration, both alkaline earth metal ions and transitional metal ions were found to lower the DNA melting temperature, indicating possible direct interaction between the divalent cations with the bases in the DNA molecules. The effectiveness increases with the order Mg 2+, Ca 2+, Mn 2+, Co 2+ and Ni 2+. It was found for the first time that the presence of Mn 2+ triggered the biphasic-melting behavior of the Salmon Sperm DNA when the concentration of the cation was increased to a value about 2 times of phosphorous in DNA.

十六烷基三甲基溴化铵对DNA热稳定性的影响

研究十六烷基三甲基溴化铵 (CTAB)对 DNA分子热稳定性的影响对于认识阳离子表面活性剂与 DNA二者之间的相互作用具有重要的意义。用差示扫描量热法和变温紫外光谱法研究了CTAB对鲑鱼精 DNA及降解的鲱鱼精 DNA热稳定性的影响 ,发现 CTAB使鲑鱼精 DNA的热稳定性降低 ,但降低程度随 CTAB浓度的增大而先增大后减小 ;CTAB使鲱鱼精 DNA发生了两阶段熔解行为。