A hammerhead ribozyme cleaves its target RNA during RNA preparation.

A chemically modified hammerhead ribozyme was designed to cleave the tax RNA of human T cell leukemia virus type I. This ribozyme was exogenously delivered to tax-transformed fibroblasts by DOTAP-mediated transfection. The analysis of RNA from ribozyme-transfected cells by RNase protection detected ribozyme cleavage products. However, control experiments revealed that the ribozyme did not cleave its target RNA intracellularly but during the course of the RNA isolation. This suggests that great care should be exercised when interpreting in vivo results of ribozyme cleavage.