Role of the stereochemistry of 3′‐fluoro‐3′‐deoxy analogues of 2‐5A in binding to and activation of mouse RNase L

Abstract

Abstract. The synthesis of two sets of analogues of 2-5A trimer containing 943-fluoro-3-deoxy-P-D-xylo-furanosy1)adenine (AF) or 3'-fluoro-3'-deoxyadenosine (A F) at different positions of the chain is described, along with the preparation of the corresponding 5'-monophosphates and 5'-diphosphorylated (core) trimers. The ability of each rib0 and xylo isomeric pair of fluorodeoxy analogues of 2-5A ( i ) to compete with p3(A2'p),A3'[32P]pC3'p for binding to RNase L in L929 cell extracts, and (ii) to activate the partially purified RNase L from L,, cell extracts to hydrolyze p~l y ( U ) [~H ] , was compared to that of the related 3'-deoxy analogue [Torrence et al., J . Biol. Chem. 263, 1131(1988] and the parent trimer, p3A,, using radiobinding and RNase L-(2'Jr)pentaadenylate(core)-agarose assays, respectively. Evidence is presented to show that the stereochemistry of the trimers plays an important role, specifically in the second process. The most striking observation is that, compared to 2-5A, p3A(AF)A was found to be nine times more effective an activator of RNase L, whereas isomeric p3A(AF)A is 30 times less effective.

Modified (2′,5′)Oligonucleotides: The Influence of Structural and Steriochemical Factors on Biological and Immunotropic Activity

“…The study of the ability of 2-5A fluorodeoxyanalogs to bind and activate RNase L showed that the analog whose fluorine atom in the xylo-configuration in the midmoiety is nine times more active than the parent mediator, 2-5A and about 280 times more effective than isomeric ribo-trimer [32][33][34]. The results suggest that anti↔syn stereochemical differences between pppAA(A F ) and pppAA(A F ), on the one hand, and related 8-bromo-and -methyl-analogs, on the other hand, cause differences in the degree of RNase L activation.…”

“…The results suggest that anti↔syn stereochemical differences between pppAA(A F ) and pppAA(A F ), on the one hand, and related 8-bromo-and -methyl-analogs, on the other hand, cause differences in the degree of RNase L activation. Data presented in [32][33][34] suggest the syn-orientation is a major contribution to this process. The pppA(A F )A F poor ability to activate RNase L supports this assumption.…”