ananyo writes "Proteins are an enormous molecular achievement: chains of amino acids that fold spontaneously into a precise conformation, time after time, optimized by evolution for their particular function. Yet given the exponential number of contortions possible for any chain of amino acids, dictating a sequence that will fold into a predictable structure has been a daunting task. Now researchers report that they can do just that. By following a set of rules described in a paper published in Nature (abstract), a husband and wife team from David Baker's laboratory at the University of Washington in Seattle has designed five proteins from scratch that fold reliably into predicted conformations. The work could eventually allow scientists to custom design proteins with specific functions."