A rapid and simple nonradioactive method for in vitro testing of ribozyme activity.

Ribozymes that target specific messenger RNA transcripts are powerful tools in the emerging fields of functional genomics, proteomics, and metabolomics. We have found that successful in vitro testing greatly increases the likelihood of producing ribozymes with good efficacy in living cells. A rapid and simple nonradioactive method for systematic in vitro testing of ribozyme-cleaving activity is reported. Ribozymes are synthesized enzymatically from double-stranded DNA (dsDNA) oligonucleotides without vector cloning. Substrate target DNA template is cloned into a vector flanked with SP6 and T7 promoters at multiple cloning sites that permit colorimetric screening and ampicillin selection, enhancing the efficiency of the cloning procedure. Ribozyme cleavage products are satisfactorily resolved on 2.0% NuSieve 3:1 agarose (FMC Products, Rockland, ME)/formaldehyde gels by electrophoresis. This method avoids the preparation of polyacrylamide gels. Using this procedure, the ribozyme, target substrate RNA, and ribozyme cleavage products are all easily detected by ethidium bromide staining. Resolution and detection are fast and simple, eliminating the need for either polyacrylamide gel analysis or radiolabeling. The use of RNase inhibitors in the assays is also assessed and discussed.