The triosephosphate isomerase barrel fold (TIM barrel fold) is one of the most widely used enzyme fold in nature. We recently succeeded in creating a de novo TIM barrel -- the first of its kind. Now we want to build on what we have learned and expand the diversity of the structures for new artificial enzymes!

The structure consists of of 8 strands and 8 helices. The 8 strands come together to form a barrel on the inside of the protein, and the helices are on the exterior to complete this two ring structure. we initially set it up with 4-fold symmetry to try to understand the fold. Now a new batch of calculations on Rosetta@Home are testing 2-fold symmetric setup. They look like two half circles trying to find ways to reach a full circle (barrel)!

here's a recent C&EN coverage on the project.
http://cen.acs.org/articles/93/i47/Protein-Designers-Roll-Barrel.html