While some enzymes are made of RNA (known as ribozymes), the vast majority of enzymes are proteins.

Here's why:

* Structure: Proteins have complex, three-dimensional structures that allow them to bind specifically to their substrates (the molecules they act upon). This specificity is crucial for enzymes to catalyze specific reactions.

* Active Site: Enzymes have a special region called the active site, where the substrate binds and the chemical reaction occurs. This site is formed by the unique arrangement of amino acids within the protein.

* Catalytic Activity: The amino acids within the active site are responsible for the catalytic activity of the enzyme. They can facilitate bond breaking and formation, helping the reaction proceed faster.

While RNA can act as a catalyst, it is much less common than protein enzymes.