Adsorption and two-dimensional condensation of 5-methylcytosine.
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.
Fojt
Lukás
L
Institute of Biophysics ASCR, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic. fojt@ibp.cz
Vetterl
Vladimír
V
Doneux
Th
T
D044503:5-Methylcytosine / Q000737:chemistry*; D000327:Adsorption; D025802:Electric Capacitance; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008628:Mercury / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
D044503:5-Methylcytosine; D006046:Gold; D008628:Mercury