Trends and Challenges in Directed Evolution

One of the convergence points of chemistry and biology is the synthesis of fine chemicals using enzymes as catalysts. Since many of these catalysts are not very efficient in typical conditions for organic synthesis, directed evolution has emerged in the last fifteen years as a powerful tool to improve the activity, selectivity and stability of enzymes. Directed evolution methods have been widely and successfully applied in the development of catalysts with improved properties. Nevertheless, this methodology is neither powerful enough to meet every catalyst properties, nor is suitable for the creation of new enzymatic activities. The recent advances and challenges in directed evolution, highlighting the problems of introducing genetic diversity coupled to Darwinian positive selection, are reviewed.