Synthesis, incorporation efficiency, and stability of disulfide bridged functional groups at RNA 5 '-ends

Modified guanosine monophosphates have been employed to introduce various f unctional groups onto RNA 5'-ends. Applications of modified RNA 5'-ends inc lude the generation of functionalized RNA libraries for in vitro selection of catalytic RNAs, the attachment of photoaffinity-tags for mapping RNA-pro tein interactions or active sites in catalytic RNAs, or the nonradioactive labeling of RNA molecules with fluorescent groups. While in these and in si milar applications a stable linkage is desired, in selection experiments fo r generating novel catalytic RNAs it is often advantageous that a functiona l group is introduced reversibly. Here we give a quantitative comparison of the different strategies that can be applied to reversibly attach function al groups via disulfide bonds to RNA 5'-ends. We report the preparation of functional groups with disulfide linkages, their incorporation efficiency i nto an RNA library, and their stability under various conditions. (C) 2000 Elsevier Science Ltd. All rights reserved.