Dear Saurabh, It's well known that good-looking crystals can have poor internal order, and therefore yield poor diffraction, and vice versa. As others have pointed out, it's crucial to check the quality of diffraction at room temperature (RT).
Just to add a bit to that: There's a nice book that assembled many tricks of the trade, including on RT experiments: Terese M. Bergfors (Ed.). Protein Crystallization. 2nd edition. La Jolla, CA, US: International University Line, 2009. The 1st edition had a nice glossary of terms with detailed tips on different chemicals, etc. This glossary was dropped in the 2nd edition but may also be a helpful read. Also see the excellent (open-access) article: Elspeth F. Garman & Robin Leslie Owen. "Cryocooling and radiation damage in macromolecular crystallography." Acta Cryst. (2006). D62, 32–47 <https://journals.iucr.org/d/issues/2006/01/00/ba5085/ba5085.pdf>. Prof. Garman recommends working with 2x stock solutions of your conditions that worked in producing crystals and using this to generate, e.g., 5% through 35% cryoprotectant solutions (in 5% steps) to probe cryoprotection---possibly stabilizing the 1x solution further by increasing the concentration of the mother liquor in it by up to ca. 4% in comparison with the original (Bergfors book, p. 163). Alexander McPherson's classic "Crystallization of Biological Macromolecules" also appears to be back in print: an excellent decision there by the publisher. Hope that helps. Good luck. Best wishes, Navdeep --- Dr. Navdeep Singh Sidhu https://scholar.google.de/citations?user=ZqU1AE0AAAAJ --- --- On 21.03.21 18:53, Saurabh Upadhyay wrote: > Dear All, > > I am trying to crystalize a protein, which occurs in monomeric (60kDa) > and tetrameric (240kDa) form. *The protein during crystallization was in > MES buffer pH-6 *and the method of crystallization was "*Sitting drop*" > in "*Proplex*" condition. Some of the conditions in which crystals were > obtained are: > > *1) 0.1M HEPES pH-7; 10% (w/v) PEG 4000* > *2) 0.1M Tris, pH-8; 8% (w/v) PEG 8000* > *3) 0.1M Tris, pH-8; 25% (v/v) PEG 400* > > For reference, I have attached the images of the crystals observed below. > > *However, the diffraction pattern obtained and the resolution of > crystals were very poor. Even some mosaicity has been observed. * > * > * > Kindly suggest some methods or modifications, to improve the resolution > and diffraction pattern of the crystals obtained. > > Thanking You, > Sincerely, > Saurabh Upadhyay, > Ph.D. Scholar > c/o Dr. Ashok kumar Patel, > Kusuma School of Biological Sciences, > Indian Institute of Technology, Hauz Khas, > New Delhi-110016, India > > > ------------------------------------------------------------------------ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > <https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1> > ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
