Ribozimi

Ribozimi, known in English as ribozymes, are RNA molecules that possess catalytic activity. Unlike most enzymes, which are proteins, ribozymes can accelerate chemical reactions such as RNA cleavage and ligation. They achieve catalysis by folding into specific three‑dimensional shapes that form an active site, often relying on metal ions like magnesium to assist catalysis. The ribosome, the cellular machine that builds proteins, is the largest known ribozyme, catalyzing peptide bond formation within its peptidyl transferase center.

The concept of RNA as an enzyme emerged from the discovery of self-splicing ribozymes in the early 1980s, notably in the Tetrahymena group I intron. This work demonstrated that RNA alone could catalyze a biological reaction, contributing to the 1989 Nobel Prize in Chemistry awarded to Thomas Cech and Sidney Altman for their discoveries concerning catalytic properties of RNA.

Ribozymes can act in cis, where an RNA molecule catalyzes a reaction on itself, or in trans, where a separate RNA substrate participates in the reaction. Catalytic strategies include acid-base chemistry and metal-ion catalysis, with Mg2+ playing a common role. Notable examples include self-splicing introns (group I and II), hammerhead and hairpin ribozymes, and the glmS ribozyme, which functions as a metabolite‑activated ribozyme using glucosamine-6-phosphate as a cofactor.

Significance and applications: ribozymes provide evidence for the RNA world hypothesis, suggesting RNA could store information and catalyze reactions in early life. In modern biology, they serve as tools for RNA cleavage and ligation in research, and have potential in biotechnology and therapeutic development, though challenges remain in stability, delivery, and specificity.