Dear all, I am trying to solve the structure of a protein complex, via MR, and when the phasing is complete there is 1/3 of the unit cell that is missing electron density. The density present looks very good and shows helices in regions that were disordered in my NMR model, suggesting that it is correct. I have also tried phasing as P1, C2, P3, and P6 all yielding the missing density. I have tested for twinning, thinking this might be the problem, using the Yeates server and it shows that there is partial twinning with a fraction of .48 and a transformation matrix of 1 0 0 -1 -1 0 0 0 -1. Also, 3 other crystals have showed this missing density and had twin fractions from .46-.48. Although it is twinned, I am not sure how this would cause an entire region of the unit cell to be missing and the crystal would not be able to form with an entire layer not ordered. So my question, to whoever is still reading, is what could be going on here? Thanks in advance.
Robert
