View Single Post
  #1  
Unread 04-23-2019, 07:54 PM
nmrlearner's Avatar
nmrlearner nmrlearner is offline
Senior Member
 
Join Date: Jan 2005
Posts: 23,134
Points: 193,617, Level: 100
Points: 193,617, Level: 100 Points: 193,617, Level: 100 Points: 193,617, Level: 100
Level up: 0%, 0 Points needed
Level up: 0% Level up: 0% Level up: 0%
Activity: 50.7%
Activity: 50.7% Activity: 50.7% Activity: 50.7%
Last Achievements
Award-Showcase
NMR Credits: 0
NMR Points: 0
Downloads: 0
Uploads: 0
Default Stability of Nitroxide Biradical TOTAPOL in Biological Samples

Stability of Nitroxide Biradical TOTAPOL in Biological Samples

Publication date: Available online 22 April 2019

Source: Journal of Magnetic Resonance

Author(s): Kelsey McCoy, Rivkah Rogawski, Olivia Stovicek, Ann McDermott

Abstract

We characterize chemical reduction of a nitroxide biradical, TOTAPOL, used in dynamic nuclear polarization (DNP) experiments, specifically probing the stability in whole-cell pellets and lysates, and present a few strategies to stabilize the biradicals for DNP studies. DNP solid-state NMR experiments use paramagnetic species such as nitroxide biradicals to dramatically increase NMR signals. Although there is considerable excitement about using nitroxide- based DNP for detecting the NMR spectra of proteins in whole cells, nitroxide radicals are reduced in minutes in bacterial cell pellets, which we confirm and quantify here. We show that addition of the covalent cysteine blocker N-ethylmaleimide to whole cells significantly slows the rate of reduction, suggesting that cysteine thiol radicals are important to in vivo radical reduction. The use of cell lysates rather than whole cells also slows TOTAPOL reduction, which suggests a possible role for the periplasm and oxidative phosphorylation metabolites in radical degradation. Reduced TOTAPOL in lysates can also be efficiently reoxidized with potassium ferricyanide. These results point to a practical and robust set of strategies for DNP of cellular preparations.



Graphical abstract







More...
Reply With Quote


Did you find this post helpful? Yes | No