ribozime

Ribozime, more commonly spelled ribozyme, is an RNA molecule that acts as a catalyst to accelerate chemical reactions. Unlike most enzymes, which are proteins, ribozymes derive their catalytic activity from their RNA sequences and three‑dimensional folds. They can catalyze reactions such as RNA strand cleavage and ligation, peptide bond formation in some systems, and the processing of RNA transcripts.

Ribozymes were discovered in the early 1980s by Thomas Cech and Sid Altman, a finding that showed RNA could have enzymatic function. Notable natural ribozymes include self‑splicing introns (group I and II) that remove noncoding sequences from RNA, the RNA component of RNase P involved in tRNA maturation, and various viral and plant ribozymes such as hammerhead, hairpin, and the glmS ribozyme that responds to small molecules. Many ribozymes operate without proteins, although some require protein cofactors for optimal activity or stability.

Mechanistically, ribozymes use the RNA’s own nucleotides—often in conjunction with metal ions such as Mg2+—to catalyze reactions. The active site is formed by a precise three‑dimensional arrangement of bases and backbone, enabling acid–base chemistry or metal‑assisted catalysis. Structural diversity among ribozymes underpins a range of reactions, from cleavage and ligation to nucleotide modification.

Biological and evolutionary significance is substantial: ribozymes participate in RNA processing, gene regulation, and viral replication. Their existence supports hypotheses about an RNA world in which RNA both stored genetic information and performed catalysis. In biotechnology, ribozymes have been explored for gene‑knockdown strategies and diagnostic tools, although therapeutic applications face challenges in delivery and stability.