RESUMO
Certain RNA molecules can mediate their own splicing, cleavage or act as enzymes to promote reactions on substrate RNA molecules. Thus, RNA is not restricted as being a passive carrier of genetic information but can have an active role in directing cellular biochemistry. Ribozymes are catalytic metallo-RNA molecules in which metal ions are essential for sufficient chemical catalysis and are often required for stabilization of ribozyme structure. Ribozymes can be used as sequence- specific RNA cleavage agents in vitro, providing useful tools for biochemical studies of RNA. These non protein biocatalysts have significant promise as therapeutic agents for diseases such as AIDS, cancer and viral hepatitis because they can be targeted against the RNA of the invading organisms responsible for these diseases and thus prevent their replication within the host cells