Yes, it is very common. I solved two of them at 2-3 A resolution and saw my colleague had one with 1.4 A resolution (can't remember the name of the protein). Please see references
J Med Chem. 2010 Jul 22;53(14):5229-39. doi: 10.1021/jm100377f. Complexes of bacterial nicotinate mononucleotide adenylyltransferase with inhibitors: implication for structure-based drug design and improvement. Huang N, Kolhatkar R, Eyobo Y, Sorci L, Rodionova I, Osterman AL, Mackerell AD, Zhang H. Chem Biol. 2009 Aug 28;16(8):849-61. doi: 10.1016/j.chembiol.2009.07.006. Targeting NAD biosynthesis in bacterial pathogens: Structure-based development of inhibitors of nicotinate mononucleotide adenylyltransferase NadD. Best, Nian On Mon, Jan 7, 2013 at 4:28 AM, Xiaopeng Hu <huxp...@mail.sysu.edu.cn> wrote: > > Dear All, > > We recently resolved an enzyme/inhibitor complex structure. The enzyme > contains two NCS related active site and we did find extra density in both of > them.However we observed that the two inhbitor moleculors are not NCS > related, but partly overlaped if make a NCS moleculor. Has anyone else > observed this before? Thanks for any help and suggestion! > > > Best, > > Xiaopeng Hu >
