Strings of contiguous modified pentanucleotides with increased DNA-binding affinity can be used for DNA sequencing by primer walking.

Modified oligonucleotides containing 5-methylcytidine and/or 2-aminoadenosine form tighter hybrids with DNA and are, therefore, more efficient primers for DNA sequencing as compared to their natural counterparts. Strings of contiguous modified pentanucleotides can be used for DNA sequencing by primer walking.