Characterization of an HDV ribozyme which consists of three RNA oligomer strands.

Properties of a mutant hepatitis delta virus (HDV) ribozyme which consists of three RNA oligomer strands (Fig. 1c) are described. Effects of the MgCl2 concentration, pH and temperature on the cleavage reaction were examined. The dependence on these conditions did not resemble those of the published data for other HDV ribozymes (the parent) which consist of single-strand RNA of about 90 nt. The highest cleavage for the mutant was observed at 35-40 degrees C, while the parent ribozymes show higher activity at around 60 degrees C than at 40 degrees C. Thus we suppose that the most of the parent ribozymes are in inactive conformation at 40 degrees C and high temperature is needed to change the equilibrium between the inactive and active conformations. Since the Tm of the mutant was around 50 degrees C, these results suggest that the most of the mutant ribozyme complex molecules are in active conformation at 40 degrees C.