Conformational principles of nucleic acids

Abstract

From a conformational standpoint, nucleic acids are enormously complex. In order to rigorously describe, for example, the secondary structure of a repeating polynucleotide such as fibrous poly dA·dT, the values of twelve torsion angles must be ascertained (Figure 1.1); contrast this with a repeating polypeptide where only two conformation angles need be determined to describe its secondary structure. For a relatively small single-stranded nucleic acid with tertiary structure such as tRNA, a complete conformational description necessitates the determination of almost one thousand torsion angle values. The challenging task undertaken in nucleic acid structural studies is, therefore, to elucidate the principles which underly the folding of polynucleotides, and ultimately to be able to predict structures.