Structure-function relationship of three triple-helical nucleic acids

The nucleic acid triplexes poly d(T).poly d(A).poly d(T), poly (U).poly (A).poly (U), and poly (I).poly (A).poly (I) display a sort of continuity between each other. However, their morphologies present their own individuality which, considering those of their parent duplexes, are quite unexpected. This comparison helps to understand tripler structure-function relationship. While helical parameters are functions of the sugar pucker, low values of WC and Hoogsteen base-pair propellers is commonplace for triplexes and the Hoogsteen base-pair geometry monitors the effects of the interstrand phosphates charge-charge repulsion.