With those statistics, it seems most probable that these two crystals
are the same protein. Do your two target proteins share an expression
system and/or purification protocol that could lead to the same
contaminant in both? If you have the resolution you could try Arcimboldo
to get an initial solution and perhaps infer the sequence from the
density. If you have crystals to spare you could digest one and identify
it via tandem mass spec. You might also try ContaMiner.
Good luck!
Tristan
On 2017-06-17 09:07, dongxiaofei wrote:
Dear ALL,
I got two kinds of crystals of different proteins ,but there are many
similarities.
The shape of the crystals are similar, the cell parameters are also
similar :
protein A , 136.12 94.398 89.476 90 125.479 90 , Space group C 1 2 1
and
protein B , 136.14 94.369 89.115 90 125.495 90 , Space group C 1 2 1.
protein A has a NMR structure ,but Rfree always high above 50% after
molecular replacement , protein B’s Rfree is also above 50% .
So I am wonder if these crystals are the result of debris of proteins
, because the growth of the crystals needs more than half a year . I
am sure the two proteins are different and crystals respectively come
from different proteins
Any insights will be really appreciated.
Thanks
Dong Xiao
