[ccp4bb] A crystallisation screen pH query.
Does anyone know the pH of JCSG+ condition A3 which is stated as 0.2 M ammonium citrate dibasic, 20% (v/v) PEG3350. I can't really measure it myself, so any help much appreciated! To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
Re: [ccp4bb] A crystallisation screen pH query.
Although it sounds as though this condition was not pH adjusted by the company, here are a couple of suggestions that are applicable to ANY commercial screen condition. 1) Try looking at the company's web site for details on how the solution was made, or failing that, try calling the company where you bought the screen and ask (you don't specify the company in your question). 2) Take a small drop of the screen solution from the reservoir well and apply it to pH paper, it'll give you an approximate idea. Don't forget that the protein and the contents of the protein buffer solution will also affect the pH in the mother liquor. Diana ** Diana R. Tomchick Professor Departments of Biophysics and Biochemistry UT Southwestern Medical Center 5323 Harry Hines Blvd. Rm. ND10.214A Dallas, TX 75390-8816 diana.tomch...@utsouthwestern.edu (214) 645-6383 (phone) (214) 645-6353 (fax) From: CCP4 bulletin board on behalf of Jon Cooper <0c2488af9525-dmarc-requ...@jiscmail.ac.uk> Sent: Saturday, October 5, 2019 4:09 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] A crystallisation screen pH query. WARNING: This email was sent from an external source. Please be cautious of links or attachments, and validate the sender's email address before replying. Does anyone know the pH of JCSG+ condition A3 which is stated as 0.2 M ammonium citrate dibasic, 20% (v/v) PEG3350. I can't really measure it myself, so any help much appreciated! To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 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/webadmin?SUBED1=CCP4BB&A=1
Re: [ccp4bb] A crystallisation screen pH query.
As was suggested, you can take a small drop and use pH paper to get a rough idea of the pH. The pH will go acidic over time as you have 20% PEG in there. This is an issue with all PEG conditions, so your specific pH will not be known by someone outside your lab as they don't know how old your screen is (and whether you've kept it frozen, in the fridge, at room temp, etc). Best of luck, tom Tom Peat Proteins Group Biomedical Program, CSIRO 343 Royal Parade Parkville, VIC, 3052 +613 9662 7304 +614 57 539 419 tom.p...@csiro.au From: CCP4 bulletin board on behalf of Jon Cooper <0c2488af9525-dmarc-requ...@jiscmail.ac.uk> Sent: Sunday, October 6, 2019 8:09 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] A crystallisation screen pH query. Does anyone know the pH of JCSG+ condition A3 which is stated as 0.2 M ammonium citrate dibasic, 20% (v/v) PEG3350. I can't really measure it myself, so any help much appreciated! To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
Re: [ccp4bb] A crystallisation screen pH query.
Many thanks for the excellent replies. I am very happy with the value of 5.1 which two of you kindly sent.Best wishesJon CooperOn 5 Oct 2019 22:51, Bob Cudney wrote: Hello Jon, That JCSG+ reagent is a copy of Hampton Research PEG/Ion reagent 48. While there is no pH adjustment made during the formulation of this reagent, the 20% w/v PEG 3350, 0.2 M Ammonium citrate dibasic in deionized water results in a measured pH at 25 degrees Celsius of 5.1. The formulation as well as measured pH, refractive index, conductivity and other details can be found here https://hamptonresearch.com/product-PEG-Ion-PEG-Ion-2-PEG-Ion-HT-11.html under the Support Material(s). Hope this helps. Kind Regards, Bob Cudney From: CCP4 bulletin board On Behalf Of Jon Cooper Sent: Saturday, October 5, 2019 2:10 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] A crystallisation screen pH query. Does anyone know the pH of JCSG+ condition A3 which is stated as 0.2 M ammonium citrate dibasic, 20% (v/v) PEG3350. I can't really measure it myself, so any help much appreciated! To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
