物理学报
物理學報
물이학보
2013年
11期
546-551
,共6页
电泳迁移率%平衡离子%动态光散射%DNA
電泳遷移率%平衡離子%動態光散射%DNA
전영천이솔%평형리자%동태광산사%DNA
electrophoretic mobility%counter-ions%dynamic light scattering%DNA
利用动态光散射技术系统地研究了不同化合价的平衡离子氯化钠(Na+)、氯化镁(Mg2+)、三氯六氨络合钴([Co(NH3)6]3+)和精胺([C10N4H30]4+)与DNA之间的相互作用.实验结果显示,当缓冲液中只包含Na+或Mg2+,且浓度c≥5 mM时, DNA电泳迁移率之比约为2:1;当缓冲液单独包含Na+或[Co(NH3)6]3+,且浓度c≥5 mM时, DNA的电泳迁移率之比约为4.5:1.而当平衡离子的化合价为4时,观察到DNA的电泳迁移率由负变正,意味着发生了电荷反转.在平衡离子浓度c<5 mM时,随着离子浓度的增大,迁移率之比逐渐增大.对于一价或二价平衡离子情形,实验结果与Manning的平衡离子凝聚理论的预言相符.对于三价平衡离子,实验结果与理论值有明显偏离.而对于四价离子,由于发生了DNA电荷逆转,基于平均场的平衡离子凝聚理论失效.另外,通过原子力显微镜观察到当平衡离子的化合价大于等于3时, DNA分子的构型发生变化.因此,自由溶液中的聚电解质的构型和离子关联效应在聚电解质迁移过程中起重要作用.
利用動態光散射技術繫統地研究瞭不同化閤價的平衡離子氯化鈉(Na+)、氯化鎂(Mg2+)、三氯六氨絡閤鈷([Co(NH3)6]3+)和精胺([C10N4H30]4+)與DNA之間的相互作用.實驗結果顯示,噹緩遲液中隻包含Na+或Mg2+,且濃度c≥5 mM時, DNA電泳遷移率之比約為2:1;噹緩遲液單獨包含Na+或[Co(NH3)6]3+,且濃度c≥5 mM時, DNA的電泳遷移率之比約為4.5:1.而噹平衡離子的化閤價為4時,觀察到DNA的電泳遷移率由負變正,意味著髮生瞭電荷反轉.在平衡離子濃度c<5 mM時,隨著離子濃度的增大,遷移率之比逐漸增大.對于一價或二價平衡離子情形,實驗結果與Manning的平衡離子凝聚理論的預言相符.對于三價平衡離子,實驗結果與理論值有明顯偏離.而對于四價離子,由于髮生瞭DNA電荷逆轉,基于平均場的平衡離子凝聚理論失效.另外,通過原子力顯微鏡觀察到噹平衡離子的化閤價大于等于3時, DNA分子的構型髮生變化.因此,自由溶液中的聚電解質的構型和離子關聯效應在聚電解質遷移過程中起重要作用.
이용동태광산사기술계통지연구료불동화합개적평형리자록화납(Na+)、록화미(Mg2+)、삼록륙안락합고([Co(NH3)6]3+)화정알([C10N4H30]4+)여DNA지간적상호작용.실험결과현시,당완충액중지포함Na+혹Mg2+,차농도c≥5 mM시, DNA전영천이솔지비약위2:1;당완충액단독포함Na+혹[Co(NH3)6]3+,차농도c≥5 mM시, DNA적전영천이솔지비약위4.5:1.이당평형리자적화합개위4시,관찰도DNA적전영천이솔유부변정,의미착발생료전하반전.재평형리자농도c<5 mM시,수착리자농도적증대,천이솔지비축점증대.대우일개혹이개평형리자정형,실험결과여Manning적평형리자응취이론적예언상부.대우삼개평형리자,실험결과여이론치유명현편리.이대우사개리자,유우발생료DNA전하역전,기우평균장적평형리자응취이론실효.령외,통과원자력현미경관찰도당평형리자적화합개대우등우3시, DNA분자적구형발생변화.인차,자유용액중적취전해질적구형화리자관련효응재취전해질천이과정중기중요작용.
The interaction between DNA and counter-ions of different valence, including sodium chloride (Na+), magnesium chloride (Mg2+), hexammine cobalt III ([Co(NH3)6]3+), and spermine ([C10N4H30]4+), is investigated by dynamic light scattering. It is found that the ratio of electrophoretic motilities of DNA in a buffer containing Na+and Mg2+is about 2:1, when the concentration of counter-ions c≥5 mM. But the ratio of DNA motilities in a buffer containing Na+and [Co(NH3)6]3+is about 4.5:1. When c<5 mM, the ratio grows with increasing concentration of counter-ions. DNA charge reversal can be observed in the case of quadrivalent counter-ion. The experimental results are in good agreement with the Manning counter-ions condensation theory for cases of monovalent or bivalent counter-ions. However, when the valency of counter-ions is equal to three, the experimental data deviates from the expectation of the theory significantly. For the quadrivalent counter-ions, the counter-ions condensation theory, which is based on the average field, fails. Furthermore, through the atomic force microscopy, it is found that DNA molecules will condense into compact structures when the valency of counter-ions is equal to or greater than three. Thus, the conformation of polyelectrolyte in free solution and the ion correlation play an important role in the migration process of polyelectrolyte.
