[N4-甲基胞嘧啶和5-甲基胞嘧啶对DNA螺旋稳定性的影响]

[Effect of N4-methylcytosine and 5-methylcytosine on the stability of the DNA helix].

作者信息

Iurgaĭtis A P, Butkus V V, Klimashauskas S I, Ianulaĭtis A A

出版信息

Bioorg Khim. 1988 Feb;14(2):158-65.

Abstract

The thermodynamic parameters (delta H, delta S) of the helix-coil transition of self-complementary oligonucleotides d(CGCGCGCG), d(CG5mCGCGCG), d(CG4mCGCGCG), d(GGACCCGGGTCC), d(GGA5mCCCGGGTCC), and d(GGA4mCCCGGGTCC) were determined. The substitution of 4mC for C was found to decrease the melting temperature of the oligonucleotides. The destabilization effect of the two substitutions is equivalent to the change of A.T for G.C pair. The free energy decrease of the helix-coil transition due to the introduction of two 4mC into an octanucleotide was estimated to be 1,24 kcal/mol.

摘要

测定了自互补寡核苷酸d(CGCGCGCG)、d(CG5mCGCGCG)、d(CG4mCGCGCG)、d(GGACCCGGGTCC)、d(GGA5mCCCGGGTCC)和d(GGA4mCCCGGGTCC)螺旋-线圈转变的热力学参数（ΔH、ΔS）。发现用4mC取代C会降低寡核苷酸的解链温度。这两种取代的去稳定化作用相当于A.T对G.C碱基对的变化。由于在一个八聚体中引入两个4mC导致的螺旋-线圈转变的自由能降低估计为1.24千卡/摩尔。