Walker G T
Department of Chemistry, University of California, Berkeley 94720.
Nucleic Acids Res. 1988 Apr 11;16(7):3091-9. doi: 10.1093/nar/16.7.3091.
Optical thermal denaturation and circular dichroism (CD) experiments were performed with the following non-selfcomplementary duplex DNA, RNA and DNA.RNA hybrids: (I) dGAG3C3G3CTC.dGAGC3G3C3TC, (II) dGAG3m5C3G3m5CTC.dGAGm5C3G3m5C3TC, (III) rGAG3C3G3CUC.rGAGC3G3C3UC, (IV) dGAG3C3G3CTC.rGAGC3G3C3UC, (V) rGAG3C3G3CUC.dGAGC3G3C3TC, (VI) dGAG3m5C3G3m5CTC.rGAGC3G3C3UC, (VII) rGAG3C3G3CUC.dGAGm5C3G3m5C3TC. Duplex stabilities (delta G degrees at 60 degrees C) increase in the order: I less than IV less than II = V = VI less than VII less than III. Large enthalpic stabilization is associated with intrastrand stacking of guanosine (rG) residues. CD spectroscopy indicates B-form conformations for the unmethylated and methylated DNA (I,II), A-form geometry for the RNA (III), and DNA.RNA hybrid (IV - VII) conformations resembling but not identical to A-RNA. C5-methyldeoxycytidine does not significantly influence DNA conformation, DNA.RNA hybrid formation, or the ability of DNA to adopt an A-type conformation in trifluoroethanol solutions.
使用以下非自互补双链DNA、RNA和DNA-RNA杂交体进行了光热变性和圆二色性(CD)实验:(I)dGAG3C3G3CTC.dGAGC3G3C3TC,(II)dGAG3m5C3G3m5CTC.dGAGm5C3G3m5C3TC,(III)rGAG3C3G3CUC.rGAGC3G3C3UC,(IV)dGAG3C3G3CTC.rGAGC3G3C3UC,(V)rGAG3C3G3CUC.dGAGC3G3C3TC,(VI)dGAG3m5C3G3m5CTC.rGAGC3G3C3UC,(VII)rGAG3C3G3CUC.dGAGm5C3G3m5C3TC。双链稳定性(60℃时的ΔG°)按以下顺序增加:I<IV<II = V = VI<VII<III。大的焓稳定作用与鸟苷(rG)残基的链内堆积有关。CD光谱表明,未甲基化和甲基化的DNA(I、II)呈B型构象,RNA(III)呈A型几何结构,DNA-RNA杂交体(IV - VII)的构象类似于但不同于A-RNA。5-甲基脱氧胞苷对DNA构象、DNA-RNA杂交体形成或DNA在三氟乙醇溶液中采用A型构象的能力没有显著影响。