Firas Khatib, Frank DiMaio, Foldit Contenders Group, Foldit Void Crushers Group, Seth Cooper, Maciej Kazmierczyk, Miroslaw Gilski, Szymon Krzywda, Helena Zábranská, Iva Pichová, James Thompson, Zoran Popović, Mariusz Jaskolski and David Baker. Crystal structure of a monomeric retroviral protease solved by protein folding game players.