Fig. 1. The anatomy of the retrosynthesis tool. In this work, we make two major contributions. First, components (1) (‘Retrosynthesis’) and (2) (‘Retrosynthesis guidance strategy’) take a holistic approach to enzymatic synthesis planning by using a large database of enzymatic transformations. They yield a diverse set of single-step suggestions to enzymatically synthesize a target compound. Then, component (3) (‘Evolution scoring’) uses a statistical model to avoid candidate reactions that are unlikely to work experimentally.