Synthesis and physical characterization of DNA fragments containing N4-methylcytosine and 5-methylcytosine

摘要

The synthesis of N4-methyl-2'-deoxycytidine and its fully protected mononucleotlae, suitable for the oligonucleotide synthesis by phosphotriester method is described, A set of octanucleotides - d(CGCGCGCG), d(CG5mCGCGCG), d(CG4mCGCGCG) and dodecanucleotides - d(GGACCCGGGTCC), dfGGA5mCCCGGGTCC). d(GGA4mCCCGGGTCC) has been synthesized in a solution. Physical characterization of the oligonucleotide duplexes by means of UV and CD spectrometry provides the evidence that 4mC similarly to 5mC favours the B↑Z transition, although both of these methylated cytosines inhibit the B↑A conformational change. N4-Methylcytosine in contrast to 5-methyIcytosine reduces the DMA double nellx thermal stability.