Studies on transfer ribonucleic acids and related compounds. XXVI. Circular dichroic properties of cyclic oligoribonucleotides and their linear counterparts

Abstract
The CD spectra of cUpUp, cCpCp, and cGpGp derived from DCC‐catalyzed polymerization of the relevant protected ribonucleoside 3′‐phosphates are described. Similar studies on Up, U > p, and cUp, as well as cUpUpUp and cUpUpUpUp, are presented. The spectral properties of the cyclic oligomers are compared with those of the corresponding linear oligomers with terminal 3′‐phosphates so as to demonstrate that disruption of normal right‐handed base stacking is considerable in these RNA loops.