Ribozyme

A ribozyme is an RNA molecule that catalyzes a chemical reaction, a function traditionally associated with proteins. Like protein enzymes, ribozymes accelerate reaction rates and are highly specific for substrates and conditions, but their catalytic center is formed by RNA itself. Many ribozymes require divalent metal ions such as Mg2+ for activity, while others function with no metal dependence. They participate in diverse cellular processes, including RNA splicing, tRNA processing, RNA maturation, and replication. Ribozyme activity also allows RNA to act as a catalyst in vitro and in engineered systems.

The term ribozyme was coined after the discovery in the early 1980s that certain RNA molecules could catalyze reactions. Thomas Cech and his group showed self-splicing group I introns, and Sidney Altman demonstrated that RNA components of RNase P can catalyze tRNA maturation. This work earned them the Nobel Prize in Chemistry in 1989. The discovery established that RNA can have enzymatic capabilities and supported the RNA world hypothesis.

Well-known natural ribozymes include self-splicing introns (group I and II), the RNA component of RNase P, and the ribosomal RNA's peptidyl transferase center, which catalyzes peptide bond formation. Small catalytic RNA motifs such as hammerhead and hairpin ribozymes cleave or ligate RNA and have been studied extensively in nature and in vitro. In addition to natural systems, engineered ribozymes are used in research and biotechnology, where they can serve as gene-regulatory switches or therapeutic agents.

Ribozymes illustrate RNA's dual role as a genetic information carrier and a catalyst. Their study informs theories about early molecular evolution and provides tools for assays, biosensing, and targeted RNA manipulation.