DNA containing the base analogue 2-aminoadenine: preparation, use as hybridization probes and cleavage by restriction endonucleases

The base analogue 2-aminoadenine (2,6-diaminopurine, D) has been introduced at selected positions into synthetic oligodeoxyribonucleotides and DNA by the combined use of chemical and enzymatic methods. 2-aminoadenine substitution for adenine introduces changes in the minor groove of DNA and creates an additional hydrogen bond in the Watson-Crick base pair with thymine. Oligonucleotide hybridization probes containing 2-aminoadenine showed increased selectivity and hybridization strength during DNA-DNA hybridization to phage or genomic target DNA. Properties of the base analogue with respect to DNA modifying enzymes were examined. 2-aminoadenine was used to probe minor groove determinants during the treatment of DNA by 12 restriction endonucleases. Inhibition of cleavage was found for several restriction enzymes.