S161: Expanding the Boundaries of Biocatalysis

Two non-conventional applications of biocatalysis will be presented. One, the use of rational design and directed evolution to develop transcription activator-like effector nucleases (TALENs) as a highly versatile and efficient tool for genome editing.  We generated and optimized the architectures of TALENs, as well as significantly improved the activity of TALENs for genome editing in human cells.  As proof of concept, we successfully corrected the point mutation causing sickle cell disease in human induced pluripotent stem cells.  Additionally, we developed a fully-automated, high throughput method for synthesis of TALENs, which can reduce the cost of synthesis to as low as $5 per TALEN. Two, design and optimization of a novel tandem catalysis process.  Although chemical and enzymatic catalysts are beginning to be combined, reactions in which an organometallic catalyst and a metalloenzyme work cooperatively to create products that cannot be generated with either catalyst alone or in comparable yields by sequential reactions of the two catalysts have not been reported. Such reactions are challenging to achieve, in part because the milieu in which these catalysts operate are typically different. We demonstrated that these catalysts can react cooperatively in the same system. We obtained 90% yield of a single epoxide from a mixture of alkenes, a metathesis catalyst and a P450 enzyme by a combination of a dynamic equilibration of alkenes and a selective epoxidation of the cross-metathesis products. These results showed the potential of combining the two classes of catalysts as synthetic catalysts become more tolerant of functional groups and enzymes become more tolerant of organic media.