Hammerhead ribozyme, molecular model. Ribozymes are RNA (ribonucleic acid) molecules that catalyse certain biochemical reactions. Until their discovery in the 1980s, it was thought only proteins had this ability. Most ribozymes catalyse their own cleavage, or that of other RNAs, but some also have roles within ribosomes, the location of protein synthesis. Atoms are represented as spheres and are colour coded: carbon, oxygen (red), phosphorous (yellow) and nitrogen (blue). Hydrogens not shown.