Formation of Triple-Helical Nucleic Acids Studied by Using Antibodies Specific for Poly(A)•Poly(U)•Poly(U)

Abstract

The formation of the triple helix of poly(A)•poly(U)•poly(U)was studied by using antibodies specific to poly(A)-poly(U)•poly(U). The 10-11 base chain length for oligo(A) and the 20-30 base chain length for oligo(U) may be the minimum sizes required to maintain a stable triple helix. Double-stranded poly(A)•poly(U) which was the core of triple-stranded poly(A)•poly(U)•poly(U) could bind poly(U) and produce an analogue of poly(A)•poly(U)•poly(U) reactive with the antibodies even if the poly(A) or poly(U) was brominated or acetylated to the extent of 35-55%. However, brominated or acetylated poly(U) did not produce a stable triple helix with double-stranded poly(A)•poly(U).