Hi, All, I got a crystal that diffracts at 3.3A in house.The crystal size is about 0.2mm* 0.1mm * 0.2mm. At first I thought the size is fine,but it turns out the smaller ones diffract worse.I guess the reason is that the cell unit is really big (126.292 126.292 134.904 p4212, pretty big for a 10kD protein, isn't it?)
So looks like I need to grow bigger crystals in order to get better diffractions.The problems is ,every time when I set up trays, the growing conditions is not exactly the same, so I have to set up a whole tray or maybe even 2 trays , then 2 or 3 conditions will jump out with good crystals ( 2 or 3 nucleation site ) and some of the others will show lots lots of small crystals.I used NaCl as the salt, in a 4*6 tray, the [NaCl] is going from 2.0,2.05,2.1,2.15,....something like that and 0.05M does make big difference.I used Urea as the additive in this case ( 25 m ~ 100 mM) and tried 2+2,3+1,3+2, 3+1 ( 3 uL protein and 1 uL buffer ) is better than the other two cases.Right now it's growing in room temp in about a week.And crystals that not fresh got some bubbles around the edge and didn't diffract well. Does anyone have any suggestions that what I could do to improve the diffraction? Thanks a lot. Jenny
