Quantitative single-nucleotide polymorphism analysis in secondary-structured DNA by affinity capillary electrophoresis using a polyethylene glycol-peptide nucleic acid block copolymer.

To estimate allele frequency of single-nucleotide polymorphisms (SNPs) in pooled DNAs with secondary structures, an affinity capillary electrophoresis was developed using an allele-specific peptide nucleic acid probe modified with polyethylene glycol. This probe disrupted secondary structures of DNA analytes and hybridized to them during electrophoresis. Such DNA-binding capability allowed separation of the folded analytes with a single-base difference within 20 min. The feed ratio of the target allele was evaluated by calculating the peak area ratio. The averaged difference between the feed and observed ratio was 1.5%. This method should be of general applicability to quantitative SNP analyses.