Patent ID: 7052838

Claim:
A process for purifying a double-stranded DNA molecule from a solution comprising the double-stranded DNA mixed with other components, comprising contacting said double-stranded DNA molecule with a third DNA strand, said double-stranded DNA molecule comprising at least one target sequence of formula I: 5′-(R) n -(N) t -(R′) m -3′ (I) wherein: R and R′ are each a single purine base; n and m are integers less than 9, and the sum of n+m is greater than 5, wherein each purine base in regions (R) n and (R′) m may be the same or different; N is a pyrimidine-purine pair of nucleotides consisting of a single pyrimidine base and a single purine base; and t is the number of pyrimidine-purine pairs in region (N) t and is chosen from an integer ranging from 1 to less than 8, and wherein each pyrimidine and purine of each pyrimidine-purine pair may be the same or different when t is greater than 1; and wherein the pyrimidine bases of region (N) t are not consecutive but are separated by purine bases; said DNA sequence of formula I being capable of interacting with a third DNA strand so as to form a triple helix structure comprising canonical triads, noncanonical triads, or combinations thereof; and obtaining the double stranded DNA in purified form.