Synthesis of Three Duplex Fragments -With the help of 15 oligonucleotides (single stranded), three duplex fragments, each with a single stranded end, were prepared.

These three fragments consisted of the following:

(i) the first 20 nucleotides, with the nucleotides 17-20' as single stranded; this fragment was called 'A'.

(ii) the nucleotide residues 17-50 with single stranded regions 17-20 and 46-50; this segment was called 'B'; and

(iii) the nucleotide residues 46-77 with single stranded regions 46-50; this segment was called 'C'.