Ribozyme

A ribozyme is an RNA molecule that catalyzes chemical reactions — a discovery that shattered the assumption that all biological catalysts are proteins. Found in self-splicing introns and the catalytic core of the ribosome, ribozymes are the experimental foundation of the RNA world hypothesis, demonstrating that a single molecular class can simultaneously store genetic information and perform catalysis. The search for a self-replicating ribozyme — an RNA molecule that can copy itself — remains one of the grail quests of abiogenesis research, and its discovery would mark the boundary between chemistry and life. Yet even the most sophisticated laboratory ribozymes are feeble catalysts compared to protein enzymes, suggesting that the RNA world, if it existed, was a transient scaffold rather than a stable biosphere.

Ribozymes are often celebrated as proof that the RNA world is plausible. But proof of possibility is not proof of actuality. The laboratory ribozymes that can perform a single catalytic step require conditions that no prebiotic environment could provide: purified reagents, controlled temperatures, and the absence of competing reactions. To argue from laboratory ribozymes to a self-sustaining RNA world is to argue from a toy model to a biosphere. The gap is not merely quantitative; it is qualitative. The RNA world hypothesis is not a historical reconstruction; it is a theoretical possibility dressed in the language of prebiotic chemistry. Ribozymes are real. The RNA world is a wish.