Stereoselective RNA reaction with chiral 2′-OH acylating agents

Abstract

The 2′-OH groups of RNA are shown to react differentially with opposite enantiomers of chiral acylating agents, with applications in conjugation and mapping of the biomolecule.

Second-Generation Chiral Amino Acid Derivatives Afford High Stereoselectivity and Stability in Aqueous RNA Acylation

“…These latter stereoselective amino acid derivatives all reacted preferentially as R enantiomers, similar to the prior alanine derivative 8. 19 The highest stereoselectivity was observed for compound 17, at 25.2:1 (R/S), more than 6-fold greater than that observed for lead compound 8. Reactivities also varied greatly, with the most reactive compounds (3,(6)(7)(8)10,13,14) achieving the target range of conversion at remarkably low concentrations of 100 μM.…”

“…However, in a previous study, single-stranded RNA did not show marked differences in stereoselectivity along the strand for compound 8. 19 Having identified several new compounds with elevated reactivity and stereoselectivity, we chose eight (9,12−18) to examine the effects of increasing bulk (Figures 2 and S4). Tests at varied concentrations enabled an assessment of relative reactivity, and time course experiments revealed when preparatively useful conversions to RNA ester derivatives were achieved and when stereoselectivity was maximized.…”

“…20,21 Further, stereoselectivity may provide increased local site selectivity in conjugation reactions. 19 Finally, chiral 2′−OH adducts that are designed to be reversible in biological media 22 may well respond differentially to chiral enzymes and chiral small molecules in the cell. Until recently, there were no reports of stereoselectivity at preparatively useful yields in small-molecule covalent reactions with RNA.…”

“…However, in a recent study, we reported the initial finding that RNA can react differentially with enantiomers of simple chiral acylimidazole compounds. 19 Amino acid and alkoxy acid imidazolide derivatives were tested in aqueous buffers, and up to 3.9:1 diastereoselectivity was seen in preparative-yield reactions of an alanine derivative with unfolded single-stranded RNA. Yet higher selectivity (up to 16:1) was observed for local positions in folded RNA targets, where the chiral environment can be more rigidly defined.…”

“…If highly stereoselective reagents and practical high-yield reactions with RNA could be identified, then such reactions can potentially have multiple applications. For example, chiral compounds offer the possibility of elevated signal over background in RNA structure mapping . In addition, they may assist in the selection and conjugation of enantiomeric l -RNA aptamers. , Further, stereoselectivity may provide increased local site selectivity in conjugation reactions .…”