Aptamers containing sequences of nucleic acid or nucleic acid analogues bound homologously, or in novel complexes
An aptamer contains at least two parallel or antiparallel heteropolymeric nucleobase-containing sequences bonded together by Watson-Crick complementary base interaction or by homologous base interaction, provided that: (a) when the aptamer is single-stranded, the at least two sequences are bonded together by homologous base interaction; and (b) when the aptamer is a duplex and the at least two sequences are antiparallel to each other, the at least two sequences are bonded together by homologous base interaction. The aptamer can be used to bind ligands or to catalyze reactions when functioning as an aptazyme.
1. A method for binding a ligand, said method comprising:
providing an aptamer comprising at least two parallel or antiparallel heteropolymeric nucleobase-containing sequences bonded together by Watson-Crick complementary base interaction or by homologous base interaction, wherein: (a) said aptamer comprising a duplex, and said at least two sequences are bonded together by Watson-Crik complememtary base interaction with parallel directionality: (b) said aptamer comprises a duplex, and at least two sequences are bonded together by homologous base interaction with paralleli or antiparallel directionally: (c) said apatmer comprises a triplex, and said at least two sequences are bonded together by Watson-Crik complementary base interaction with parallel or antiparallel directionity: (d) said aptamer comprises a triplex, and said at least two sequences are bonded together by homologeous base interaction with parallel or antiparallel directionality; (e) said aptamer comprises a quadruplex, and said at least two sequences are bonded together by Watson-Crik complementary base interaction with parallel or antiparallel directionality and do not rely on Hoogsteen bonding and GG quartets for maintence of complex structure or (f) said aptamer comprises a quadruplex, and said at least two sequences are bonded together by homologous base interaction with parallel or antiparallel directionality and do not rely on Hoogsteen bonding and GG quartets for maintenance of complex structure; and
contacting said aptamer with said ligand to bind said ligand to said aptamer by interaction other than by Watson-Crik base pairing of nucleobase to nucleobase.
2. The method of claim 1 , wherein said providing comprises placing said aptamer in solution, on a solid support, in vitro, in vivo or in silico.
3. The method of claim 1 , wherein said providing comprises administering said aptamer to an organism.
4. The method of claim 3 , wherein said aptamer is administered in an amount effective to alter a biological activity of said ligand.
5. The method of claim 3 , wherein said aptamer is labeled and is administered in an amount effective to detect said ligand or said ligand and a second ligand bound to said ligand.
6. The method of claim 1 , wherein said providing comprises placing said aptamer in a test medium, and a presence or an absence of said ligand in said test medium is detected.
7. The method of claim 1 , wherein said aptamer comprises a duplex, and said at least two sequences are bonded together by Watson-Crick complementary base interaction with parallel directionality.
8. The method of claim 1 , wherein said aptamer comprises a duplex, and said at least two sequences are bonded together by homologous base interaction with parallel or antiparallel directionality.
9. The method of claim 1 , wherein said aptamer comprises a triplex, and said at least two sequences are bonded together by Watson-Crick complementary base interaction with parallel or antiparallel directionality.
10. The method of claim 1 , wherein said aptamer comprises a triplex, and said at least two sequences are bonded together by homologous base interaction with parallel or antiparallel directionality.
11. The method of claim 1 , wherein said aptamer comprises a quadruplex, and said at least two sequences are bonded together by Watson-Crick complementary base interaction with parallel or antiparallel directionality.
12. The method of claim 1 , wherein said aptamer comprises a quadruplex, and said at least two sequences are bonded together by homologous base interaction with parallel or antiparallel directionality.
13. The method of claim 1 , wherein said ligand comprises a protein or peptide.
14. The method of claim 1 , wherein said ligand is free of nucleobases.
15. The method of claim 1 , wherein some nucleobases in said at least two sequences are not paired.
16. The method of claim 1 , wherein said at least two sequences are contained in at least two nucleic acid strands that are cross-linked.
17. The method of claim 1 , wherein the aptamer is an aptazyme.