Extra stable 2 ',5 '-linked RNA loops

We prepared hairpins that differ in the connectivity of phosphodiester link ages in the loop (RNA vs 2', 5'-RNA). We find that the stability of the ext ra stable RNA hairpin 5'-rGGAC(UUCG)GUCC-3' is the same as that observed fo r the hairpin containing a 2',5'RNA loop, i.e. 5'-rGGAC(UUCG)GUCC-3' (where UUCG = U2'p5'U2',p5' C(2'p5')G(2'p5')). Also significant is the finding th at when the stem is duplex DNA, duplex 2,5'-RNA, or DNA:2',5'-RNA, hairpins with the UUCG loop are more stable than those with UUCG loop.