Don't be afraid of trying to shoot needles. You'll have to improve yours but it was possible for me.
I managed to increase the size of some needles to the point where I could (with great difficulty) pick them up with a loop and shoot them. The key was changing the cation from Na to Zn2 . Try varying the cation while keeping the anion constant and vice versa, plus vary the concentrations of the ions. Changing to Zn2 managed to increase the width of the needles maybe 20-fold, but they didn't diffract at our home source. At the synchtron with a smaller beam, they diffracted pretty nicely until extreme radiation damage set in after about 100 degrees of data, which was enough to solve the structure. Another key was mounting them so that a portion of the needle stuck out of the loop--completely devoid of mother liquor. There was no diffraction in the loop, probably because of background from the cryo/mother liquor, but outside of the loop I got some nice, although small, spots. ~ Peter J Stogios Ph.D. candidate, Privé Lab Dept. of Medical Biophysics, University of Toronto Toronto Medical Discoveries Tower (TMDT) at MaRS 101 College St., Rm. 4-308 Toronto, Ontario M5G 1L7 e: [EMAIL PROTECTED] w: http://xtal.uhnres.utoronto.ca/prive p: (416) 581-7543 > ---------------- Original message ------------------ >From: Ngo Duc Tri <[EMAIL PROTECTED]> >To: [EMAIL PROTECTED]> >Reply to: Ngo Duc Tri <[EMAIL PROTECTED]>-> >Subject: [ccp4bb] Optimization of needle crystals? > > Dear ccp4 users, > I crystallized a membrane protein and got some conditions showing the small > needle crystals. All condition contained Mg2 and high buffer pH. > I learn that it is difficult to optimize the needle crystal. However I > would like to ask your experience how to optimize in this case. > Here is the attached picture of my crystal. Thank you very much for your > advices! > > My best regards, > TriNgo > PhD Student - Sungkyunkwan University, Korea > > ---------------- Original message ------------------ >From: Ngo Duc Tri <[EMAIL PROTECTED]> >To: [EMAIL PROTECTED]> >Reply to: Ngo Duc Tri <[EMAIL PROTECTED]>-> >Subject: [ccp4bb] Optimization of needle crystals? > > Dear ccp4 users, > I crystallized a membrane protein and got some conditions showing the small > needle crystals. All condition contained Mg2 and high buffer pH. > I learn that it is difficult to optimize the needle crystal. However I > would like to ask your experience how to optimize in this case. > Here is the attached picture of my crystal. Thank you very much for your > advices! > > My best regards, > TriNgo > PhD Student - Sungkyunkwan University, Korea >
