Sequence-specific binding polymers for duplex nucleic acids

Claim 1

A polymer composition effective to bind in a sequence-specific manner to a target sequence of a duplex polynucleotide containing different Watson-Crick basepair orientations at selected target sequence positions, comprising a selected sequence of subunits having the form: ##STR8## where Y is a 2- or 3-atom length, uncharged subunit linkage group; R is H, OH, or O-alkyl; the 5'-methylene has a β stereochemical orientation in the 5-membered ring and a uniform steroeochemical orientation in the 6-membered ring; R i has a β sterochemical orientation; and at least about 70% of R i groups in the polymer have the following target basepair-orientation specificities: (a) for a T:A or U:A orientation, R i is diaminopurine; (b) for a C:G orientation, R i is guanine or 6-thioguanine; (c) for a G:C orientation, R i is selected from the group consisting of planar bases having the following ring structures and hydrogen bonding arrays, where B indicates the polymer backbone: ##STR9## where the * ring position may carry a hydrogen-bond acceptor group; and (d) for an A:T orientation, R i is selected from the group consisting of planar bases having the following ring structures and hydrogen bonding arrays, where B indicates the polymer backbone: ##STR10## where the * ring position may carry a hydrogen-bond donating group.