Dear Deepak, the cryoprotection may destroy the diffraction. I would also try diffraction at room temperature, using special sleeves to prevent dehydration. With 20% PEG400, you could also try to freeze the crystals without using additional cryoprotectant. If you are lucky, it may work.
Best, Herman Von: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> Im Auftrag von Deepak Deepak Gesendet: Dienstag, 18. Mai 2021 12:08 An: CCP4BB@JISCMAIL.AC.UK Betreff: [ccp4bb] sugestions on weak diffracting protein crystals Dear all, I have got multiple crystals (see picture 1) of a protein (8kDa) with a helical aromatic oligoamide foldamer (5kDa) but these crystals diffract very poorly (see the diffraction pattern in picture 2). I prepare a 1.3mM:1.3mM complex of protein: foldamer in 20mM Tris, pH 7.5 buffer. Crystals grew in 3-5 days in sitting and hanging drop at 20 Deg C and 25 Deg C in the following conditions: - 20% PEG 400, 0.1M MES pH 6.0 -20% PEG 400, 0.1M Sodium Cacodylate pH 6.0 Multiple cryo used were: -25%Glycerol in mother solution -30% glycerol in water -30%PEG 400, -35% PEG 400 -20% PEG 8000 + 40% PEG 400 mix Kindly suggest some methods/modifications on how can I improve the resolution and get better-diffracting crystals. Please let me know if you need more information. Kind regards, Deepak Ph.D. Student PS: The protein is a DNA binding protein and I have crystallized and solved the structure of this protein with its DNA partner and now I crystallized it with our foldamers but diffraction is not good. There are multiple structures of the Protein+DNA complex in literature but no apo-protein structure as the protein needs a binding partner to crystallize. We already have solution studies showing a good binding. ________________________________ 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://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.jiscmail.ac.uk%2Fcgi-bin%2FWA-JISC.exe%3FSUBED1%3DCCP4BB%26A%3D1&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C49a9b7a09d664c4f081108d919e66f22%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637569299785900813%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=ELgp9Msphh8z2i4NhA7D4NZKIZiDRx%2F5pjYtITVFBI0%3D&reserved=0> ######################################################################## 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/
