Document Detail


A spectroelectrochemical cell designed for low temperature electron paramagnetic resonance titration of oxygen-sensitive proteins.
MedLine Citation:
PMID:  2554761     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In this paper we describe an anaerobic titrator made virtually from glass with a small amount of high vacuum epoxy mounted directly to a quartz EPR tube. A complete titration may be carried out with as little as 600 microliters of sample. This cell features the anaerobic manipulation of an electrochemically poised solution from an electrochemical pouch to an EPR tube. The cell uses a gold foil working electrode and Ag/AgCl reference and counter electrodes. The reference and counter electrodes are isolated from the sample by leached Vycor glass. In the work reported here, we used this cell to determine the equilibrium redox potential of methyl viologen in an EPR titration. With methyl viologen as an indicator we found that the cell has a residual oxygen level of 1.5 microM with a leak rate of 0.005 nmol/min. After moving the solution into the EPR tube, freezing, performing EPR, and thawing, the potential of the methyl viologen solution drifted only 2 mV. During the titration, the poised potentials were stable, drifting only 1 mV/min. Formal potentials as low as -630 mV in a vitamin B12-type protein have been determined with this cell (S. R. Harder, W.-P. Lu, B. A. Feinberg, and S. W. Ragsdale (1989) Biochemistry, in press).
Authors:
S R Harder; B A Feinberg; S W Ragsdale
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Analytical biochemistry     Volume:  181     ISSN:  0003-2697     ISO Abbreviation:  Anal. Biochem.     Publication Date:  1989 Sep 
Date Detail:
Created Date:  1989-11-27     Completed Date:  1989-11-27     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370535     Medline TA:  Anal Biochem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  283-7     Citation Subset:  IM    
Affiliation:
Department of Chemistry, University of Wisconsin-Milwaukee 53210.
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MeSH Terms
Descriptor/Qualifier:
Anaerobiosis
Chemical Phenomena
Chemistry
Electrochemistry
Electron Spin Resonance Spectroscopy
Hydrogen-Ion Concentration
Oxygen
Paraquat
Proteins / analysis*
Spectrophotometry, Ultraviolet
Temperature
Grant Support
ID/Acronym/Agency:
GM39451/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/Proteins; 4685-14-7/Paraquat; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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