Nearly 20 years ago, Tom Cech and Sidney Altman discovered that some naturally occurring RNAs could perform enzymatic reactions, earning these researchers the 1989 Nobel Prize in chemistry. Scientists have now identified several examples of RNA enzymes, or ribozymes. Most make or break the phosphodiester bonds in nucleic acid backbones, but some perform other reactions: The ribosome's peptidyl transferase center is also a ribozyme.1
What makes ribozymes particularly interesting is that they are amenable to tinkering. Creation of a protein enzyme de novo, or modification of an existing one to function in a different way, is a monumental, and often futile effort. But nucleic acids lend themselves to this type of research because they uniquely couple genotype and phenotype, says Scott Seiwert, group leader, diagnostic systems, Ribozyme Pharmaceuticals (RPI), Boulder, Colo. In other words, when an active ribozyme is selected, it can be cloned and sequenced directly; the same is ...
