Structure of poly (dT).poly (dA).poly (dT)

Overview of Rengaswami Chandrasekaran et al.

AuthorsRengaswami Chandrasekaran, Andrea Giacometti, Struther Arnott
Affiliation Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, IN 47907, USA  
JournalJournal of Biomolecular Structure and Dynamics
Year 2000

Abstract


The molecular structure of poly (dT).poly (dA).poly (dT) has been determined and refined using the continuous x-ray intensity data on layer lines in the diffraction pattern obtained from an oriented fiber of the DNA. The final R-value for the preferred structure is 0.29 significantly lower than that for plausible alternatives. The molecule forms a 12-fold right-handed triple-helix of pitch 38.4 A and each base triplet is stabilized by a set of four Crick-Watson-Hoogsteen hydrogen bonds. The deoxyribose rings in all the three strands have C2'-endo conformations. The grooveless cylindrical shape of the triple-helix is consistent with the lack of lateral organization in the fiber.