1. Artie McFerrin Department of Chemical Engineering, Texas A&M University , College Station, TX 77843-3122, USA
2. Department of Biology, Washington University in St. Louis , St. Louis, Missouri, 63130, USA
3. Department of Integrative Structural and Computational Biology, Scripps Research , La Jolla, CA 92037, USA
4. Department of Biology, Texas A&M University , College Station, TX 77843-3258, USA