Fishing the best pool for novel ribozymes

Novel RNA enzymes, or ribozymes, are sought in large pools of random RNA sequences. Because of the large number of random positions in an individual pool molecule, only a vanishingly small fraction of the possible sequences are actually present. Even so, increasing the length of the individual pool molecules significantly increases the probability of finding a particular complex ribozyme. Because ribozymes are typically composed of conserved sequences interleaved with regions that can vary in sequence and length, a longer molecule allows a greater number of possible arrangements of a given ribozyme motif, increasing the likelihood that it will be present in the pool. Once a ribozyme motif has been found, rational and irrational optimization techniques can be used to identify related ribozyme sequences with greater activity.