First piece of advice I have is to shove them in the beam and see what happens. A few days ago we got high-resolution data from crystals that are shaped like eggs. No edges on them whatsoever. In the past, saucer-shaped crystals diffracted to 2A whereas their hexagonal 'perfect' cousins (grown from a different PEG, if memory serves) had Cheeseburger-strength diffraction.
Secondly, if ordinary optimization attempts repeatedly fail, it may be time for protein optimization, e.g. proteolysis, mutagenesis, methylation and so forth :) Artem On Tue, Oct 26, 2010 at 3:23 PM, Matthew Bratkowski <[email protected]>wrote: > Hello. > > I have obtained disk shaped crystals of a protein that I am working on. I > got hits in about 10 different conditions, with a few common precipitants > and pHs, and I have optimized two conditions so far. In the optimized > conditions, the crystals appear overnight, usually surrounded by or hiding > under heavy precipitant. Under the best conditions, I get what I would > describe as single disks, some of which are of decent size and very round, > that rotate light very well. Sub-optimal conditions can give small to large > crystal clusters. I shot the large disk crystals grown from one conditions > at the synchrotron. but they do not diffract. > > I was wondering if anyone had any advice about optimizing these crystals in > order to get them to diffract better? As mentioned before, I have only > tried optimizing a few of the hit conditions (varying precipitant conc., pH, > etc.), but crystals from all of the hits look the same: always round disks > or disk clusters. This leads me to believe that optimized conditions of the > other hits will produce similar results as before. Would it be worthwhile > to try optimizing these conditions as well? I have also tried seeding, > which just produces a lot of clusters, and an additive screen. Some of the > additives help to produce larger crystals, but again I always get single or > disk clusters. > > Any advice would be helpful. > > Thanks, > Matt > > >
