S154: Combining computational protein design and directed evolution for generating novel biocatalysts and small molecule binders

The custom design of protein receptors and enzymes provides a rigorous test of our understanding of the principles of molecular recognition and catalysis. Successful designs will have wide-ranging applications in biosensing and ‘green' chemical synthesis. I will describe new combined computational-experimental approaches for protein design. Applications of these approaches include repurposing the reactivity of existing enzymatic active site functional groups for novel reactions, introducing new reactivity in otherwise inert scaffold proteins, and the de novo design of proteins to non-covalently bind small molecules of choice. Specifically, I will describe two recent design efforts: (a) A zinc-containing murine adenosine deaminase enzyme has been redesigned to catalyze the hydrolysis of an organophosphate pesticide with a catalytic efficiency kcat/KM ~10^4 (/Ms). (b) Computationally-designed proteins that bind the steroid digoxigenin and the vitamin biotin have been obtained. These results provide insights into the physical-chemical principles underlying molecular recognition and catalysis, and highlight avenues for further improvement of the design methodology.