Synthesis, Incorporation Eciency, and Stability of Disul®de Bridged Functional Groups at RNA 50-Ends

ÐModi®ed guanosine monophosphates have been employed to introduce various functional groups onto RNA 50-ends. Applications of modi®ed RNA 50-ends include the generation of functionalized RNA libraries for in vitro selection of catalytic RNAs, the attachment of photoanity-tags for mapping RNA±protein interactions or active sites in catalytic RNAs, or the nonradioactive labeling of RNA molecules with ̄uorescent groups. While in these and in similar applications a stable linkage is desired, in selection experiments for generating novel catalytic RNAs it is often advantageous that a functional group is introduced reversibly. Here we give a quantitative comparison of the di€erent strategies that can be applied to reversibly attach functional groups via disul®de bonds to RNA 50-ends. We report the preparation of functional groups with disul®de linkages, their incorporation eciency into an RNA library, and their stability under various conditions. # 2000 Elsevier Science Ltd. All rights reserved.