Abstract
Recent advances in the study of ribozymes are summarized. One class of ribozymes consists of three functionally different domains which are a recognition unit, a catalytic core unit and an activator unit. The ribozymes are also associated with activator protein (s) in vivo. These four functional units are independent modules. New discoveries on the origin and evolution of intron ribozymes are presented. There are two different origins of these ribozymes. The relationship between the ribozyme and spliceosome is not clear. Attempts to redesign ribozymes as antiviral reagents (RNA restriction enzymes) are also illustrated.
