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Hi Anirban, At JCSG, we subjected ~180,000 crystals from ~3500 unique/novel proteins/complexes to X-ray diffraction screening, resulting in >1500 novel structures in the PDB at an average resolution ~2.0A. In theory, if we had the bandwidth now to sort through all that data to pull out images of the mounted crystals and their diffraction quality, we could probably get some good analysis done on this. However, as an alternative, I can certainly provide some examples that we have dealt with recently that I hope will add substance to the anecdotes to motivate your trainees! a) For one protein, our first crystals were oval shaped, without sharp geometry/edges, much like a pebble. We got a high quality 1.9A structure out of it. Subsequent optimization led to much nicer looking crystals with nice shapes and we collected ~50 data sets from them all resulting in ~2A structures so not much improved compared to the initial visually poorer crystals. b) For another protein, crystals grow nicely but some of the crystals remain suspended in solution whereas other settle to the bottom and stick. For the ones which stick, some can be dislodged by gentle prodding with a nylon loop while harvesting and they result in (along with the ones that are not stuck) in ~1.8-2A structures. For the ones which are stuck and cannot be gently dislodged, a nudge with a plastic tip (out of desperation!) is sufficient to dislodge them, and they retain their nice visual appearance and shape, but have total loss in diffraction. c) We see this too for crystals soaked with ligands. In some cases after soaking the crystals appear fine but suffer in diffraction quality, and in some cases they appear to have suffered visually but result in usable data sets/structures. So at the end of the day there are crystals that appear nice but do not diffract well and there are crystals that do not appear nice but lead to good/usable structures. So it's all about inner beauty. Never give up on crystals/crystal optimization without testing them by X-rays. Best, Debanu On Thu, Jun 28, 2018 at 5:07 PM, Anirban Banerjee <[log in to unmask]> wrote: > > Dear all, > > Apologies for the non-CCP4 related question. > > If you have concrete experience about visually unappealing, i.e. ugly > crystals ( your own take on ugly is fine) diffracting better than > comparably similar sized nicer looking crystals of the same protein, will > you please share here ? Even better if that led to a published structure. > Might you also have pictures ? > > We have all heard anecdotes about not using visual appearance to judge the > quality of crystals as far as their ability to give good diffraction data is > concerned but I am trying to gather some concrete pointers here to motivate > trainees. > > Thanks very much for any help. > > Best, > > Anirban > > P.S. I know that there is probably a lot of thought and wisdom on this this > specific topic but I am really looking for actual experience. > > ________________________________ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1