Dear all,

 

I'm refining a structure and find some strange triangle density on the oxygen of Ser and Thr at the C terminus. One picture of the strange density is attached here. Could anyone please give me some suggestions on what this could be?

 

The buffer used during purification is PBS, Tris and NaCl. And crystallization condition contains PEG3,350 and Mg(NO3)2.

 

Thank you all in advance for any suggestion.

 

Best,

 

Vinson Liang