Dear ALL:
Recently we've been trying hard to crystallize a highly glycosylated protein complex ( 30% percent of carbohydrate in the total 120KD molecular weight).
IT is a high affinity protein complex. One component can be crystallized in high salt condition and the other can be crystallized in PEG.
Through screening, we happened to get some very ugly crystals in PEG condition using gel-fil purified complex sample.
The problem is that it is very hard to repeat the screening condition. In contrast, it is very
easy to get phase separation in the drop
although we tried to optimize the protein and precipitant concentration.
We tried to de-glycosylated using PNGase and EndoH but failed in non-denaturing condition.
Hampton additive screen did not help either. We tried seeding several times but so far we have not got any better luck.
Can anyone give some guidance here? Thanks a lot,
Jerry McCully
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