If you even still have a few milliliters of the original PEG solution, you could simply use that for mixing with the protein in the drop and use a different PEG solution for the reservoir, thereby ensuring a mother liquor that could either provide (or remove) a missing impurity.
Diana ________________________________ From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of Patrick Loll <pjl...@gmail.com> Sent: Monday, March 22, 2021 1:39 PM To: CCP4BB@JISCMAIL.AC.UK <CCP4BB@JISCMAIL.AC.UK> Subject: Re: [ccp4bb] Fluka-branded PEG 3000 EXTERNAL MAIL I don’t think we have any of that PEG lying around (sorry), but you might also consider that PEGs are notorious for impurities of various types; perhaps the Fluka reagent has less of an impurity that is particularly vexing for your specific protein. Of course, I suppose it might have more of a particular impurity that’s stimulating crystallization…. Here’s an older reference that talks about ways to clean up PEGs: doi: 10.1016/0003-2697(85)90544-5 I honestly don’t know if “modern” PEG reagents are less likely to contain impurities than the materials available at the time this paper was written (but the intrinsic nature of the molecule hasn’t changed, so maybe not?). Good luck. Pat Loll Patrick J. Loll, PhD (he,his) Professor of Biochemistry & Molecular Biology Drexel University College of Medicine Room 10-102 New College Building 245 N. 15th St. Philadelphia, PA 19102-1192 USA On 22 Mar 2021, at 1:00 PM, Correy, Galen <galen.cor...@ucsf.edu<mailto:galen.cor...@ucsf.edu>> wrote: Dear all, I'm wondering if anyone could spare 50-100 g of Fluka branded PEG 3000 (see attached image)? We have some crystals that diffract better when grown using Fluka PEG compared to other brands. Unfortunately, we've exhausted our supply of the Fluka PEG, and it's no longer commercially available (the same product code is available from Sigma - we've tested it, along with several other brands - but they don't seem to have the same magic as the Fluka PEG). We'll happily purchase a new bottle of Sigma-branded PEG 3000 to replace any sent our way. Many thanks, Galen ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 <fluka.png> pjl...@gmail.com<mailto:pjl...@gmail.com>, pj...@drexel.edu<mailto:pj...@drexel.edu> ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 CAUTION: This email originated from outside UTSW. Please be cautious of links or attachments, and validate the sender's email address before replying. ________________________________ UT Southwestern Medical Center The future of medicine, today. ######################################################################## 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/
