A quick glance at extant organisms it is more than enough to understand the central role of polymers in biological systems. The interaction between two molecular partners is ultimately based on their three-dimensional structure, which is the result of a well defined and stable spatial arrangement of their chemical groups. Since molecular recognition is crucial to any biological activity and is the result of a well-define folding, one can claim that the biological activity of a biopolymer is grounded on its three-dimensional structure. An important corollary to this observation is that a necessary condition to have any potential biological activity is a well defined three-dimensional structure. On the basis of this observations, the question whether a stable folding is a common feature or rare result of natural selection is of great relevance to understand the role of biopolymers in living systems.
The question becomes more intriguing if one considers that the collection of extant biopolymers represents only a small fraction of all possible ones. From this trivial observation a straightforward question arises: why has only a small ensemble of all possible biopolymers been used? Nature has not fully explored the whole space of sequences and thus there may be an entire universe of “never born biopolymers” whose properties are waiting to be discovered. From this viewpoint, the study of random biopolymer libraries is an urgent task to shed new light on the evolution of life and to unlock and exploit the full potential of biopolymers. Within this framework, in our group an investigation of the structural properties of a random RNA library has been undertaken. The main aim is to explore the realm of all-possible RNA’s, including those that might have never been sampled by Nature, the  “never born RNA’s”. Moreover, the interest in RNA lies on its possible role in the origin of Life and its recent biotechnological application. Thus, the main intent of this research project is the evaluation of the occurrence of spontaneously folded RNAs in a random library.