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:[log in to unmask]] On Behalf Of Neeraj
Sent: Friday, April 18, 2008 1:21 PM
To: [log in to unmask]
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
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