Have a look at Ray WJ Jr, Puvathingal JM. A simple procedure for removing contaminating aldehydes and peroxides from aqueous solutions of polyethylene glycols and of nonionic detergents that are based on the polyoxyethylene linkage. Anal Biochem. (1985) 146:307-12 http://dx.doi.org/10.1016/0003-2697(85)90544-5
Zhang M, Tanner JJ Detection of L-lactate in polyethylene glycol solutions confirms the identity of the active-site ligand in a proline dehydrogenase structure Acta Crystallogr. (2004). D60:985-986 http://dx.doi.org/10.1107/S0907444904003786 Regards, Mitch -----Original Message----- From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of Neeraj Sent: Friday, April 18, 2008 1:21 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] PEG oxidation Hi all....i have been trying to crystallize a protein and have had some hits with conditions having PEG in them (400 and 4000).....but everytime i have tried to reproduce the conditions there has been a lot of heterogeneity......and then to look for answers i delved a little deeper into understading about the ingredients that i have been using and discovered that PEG might actually be the culprit here.....I am using PEG 400 and 4000 and since PEGs are inherently unstable and prone to oxidation in the presence of oxygen by producing increased levels of aldehydes and peroxides which reduce the pH drasticall, I feel that this might be whats affecting the reproducibility. I was wondering if anyone has ever encountered similar scenarios and did anything with regards to fixing things for PEG. Any help would be greatly appreciated as i am a little short of ideas since things do work i cant seem to reproduce them and its very frustrating in a way. Thanks and i look forward to some helpful suggestions Neeraj -- Neeraj Kapoor TPCB Graduate Fellow Sakmar Lab/ Molecular Biology & Biochemistry The Rockefeller University 1230 York Avenue, RRB 510 New York, NY 10021 lab.1.212.327.8284:fax.7904 mobile: 917.535.2030 http://www.rockefeller.edu/labheads/sakmar/sakmar-lab.html
