The Synthetic DNA Duplex of Poly d(Abr⁵U)·Poly d(Abr⁵U) Adopts an A-DNA-Like Structure

Abstract

An X-ray fiber diffraction study of the synthetic DNA duplex poly d(Abr⁵U)·poly d(Abr⁵U) shows that its sodium salt adopts an unexceptional A-DNA-like structure. Similar to A- DNA two molecules are packed in a monoclinic unit cell (a = 2.23 nm, b = 4.14 nm, c = 5.61 nm and α = β = γ = 90°) of space group C2. Because of its dinucleotide chemical motif, the c-repeat is twice that in A-DNA but, notably, corresponding backbone conformation angles of adjacent nucleotides are almost identical. This is in marked contrast to many B-like conformations of polydinucleotides.