Fojt Lukás, Vetterl Vladimír, Doneux Th
Institute of Biophysics ASCR, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic.
Bioelectrochemistry. 2009 Jun;75(2):89-94. doi: 10.1016/j.bioelechem.2009.02.003. Epub 2009 Feb 23.
Purine and pyrimidine derivatives occurring in nucleic acids posses an extraordinary high ability of self-association at the electrode surface and can form there by a two-dimensional (2D) condensation a monomolecular compact film (self-assembled monolayer-SAM). The effects of methyl substituent on the 2D condensation were studied using the 5-methylcytosine molecule which is involved in gene silencing and has a great biological impact. At acid pHs, 5-methylcytosine forms at the mercury electrode a physisorbed self-assembled 2D layer at potentials close to the potential of electrocapillary maximum. From the temperature dependence of the electrode double layer capacitance, the standard Gibbs energy of adsorption (Delta G(m)=-12.7 kJ mol(-1)), lateral interaction coefficient of the Frumkin adsorption isotherm (a(c)=2.05) and area occupied by one molecule (A=1.31 nm(2)) in the 2D layer were determined. Measurements performed on a single-crystal Au(111) surface show that the 2D condensation can take place on other substrates as well.
核酸中存在的嘌呤和嘧啶衍生物在电极表面具有极高的自缔合能力，并且能够在那里通过二维（2D）缩合形成单分子致密膜（自组装单分子层-SAM）。使用参与基因沉默并具有重大生物学影响的5-甲基胞嘧啶分子研究了甲基取代基对二维缩合的影响。在酸性pH值下，5-甲基胞嘧啶在汞电极上于接近电毛细最大电位的电位形成物理吸附的自组装二维层。根据电极双层电容的温度依赖性，确定了吸附的标准吉布斯自由能（ΔGm = -12.7 kJ mol-1）、弗鲁姆金吸附等温线的横向相互作用系数（ac = 2.05）以及二维层中一个分子占据的面积（A = 1.31 nm2）。在单晶Au(111)表面上进行的测量表明，二维缩合也可以在其他基底上发生。
