The structure of this protein has already been solved and published, but close inspection suggests that there are some problems with the published solution. We'd like to see if Foldit players can use the same electron density data to reconstruct a better model. It's a quite large, so we would recommend the trim tool on this one. This one also has a big piece of DNA in it!
Don't be fooled, the non-protein in this puzzle is RNA, not DNA, despite the fact it forms a double helix of sorts. It's all one chain, so no sense and anti-sense to worry about.
One interesting feature of RNA is that you can't cut it. You'll see an "action not permitted on RNA" message if you try cutting it in the GUI.
For RNA, the function structure.GetDistance ( a, b ) returns the distance between atom 1 in segment a and atom 1 in segment b.
Just to be clear, for DNA and RNA, structure.GetDistance ( a, a +1 ) gives the distance between the phosphorus atom of one nucleobase (a) and the next nucleobase (a + 1).