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Why might RNA molecules have served as early catalysts before proteins evolved?

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Diagram showing how epinephrine binding to a beta-adrenergic receptor on a cell membrane activates a G-protein, which then stimulates adenylyl cyclase to convert ATP into cyclic AMP (cAMP), leading to physiological effects such as increased heart rate, blood vessel dilation, and glycogen breakdown. — Biochemistry In biochemistry, researchers study the chemical substances and processes that occur in living organisms and cells. In particular, various processes by which cells gain energy, such as epinephrine-stimulated cAMP synthesis, have been deduced through the study of biochemistry.

It is hypothesized that RNA molecules served as early catalysts before the evolution of proteins because they possess the unique ability to both store genetic information and perform enzymatic functions. This period in evolutionary history is often referred to as the "RNA world".123

RNA molecules can fold into complex three-dimensional structures, which allows them to act as biological catalysts known as ribozymes. These molecules can facilitate essential biochemical reactions, such as self-splicing or the cleavage of other RNA molecules. Furthermore, because RNA can act as a template for its own replication, it provided a mechanism for early life to propagate genetic information before the more complex machinery of protein synthesis emerged.142

While proteins are more powerful catalysts due to their chemically varied side chains, their synthesis is highly complex and requires the prior existence of RNA catalysts, such as those found in the ribosome. Consequently, RNA likely functioned as the primary catalyst and genetic repository until more stable systems, such as DNA, evolved to store information.23