If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.


Analytical Chemistry

EPR Sizes Up Histones

Electron paramagnetic resonance spin-labeling technique allows researchers to measure the dimensions of a key protein complex

by Amanda Yarnell
January 26, 2009 | A version of this story appeared in Volume 87, Issue 4

Credit: David Norman/U Of Dundee
Distances between spin-label pairs on the histone spool reveal its dimensions.
Credit: David Norman/U Of Dundee
Distances between spin-label pairs on the histone spool reveal its dimensions.

Using an electron paramagnetic resonance spin-labeling technique, researchers in the U.K. have ma9naged to take measurements of histone proteins (J. Am. Chem. Soc., DOI: 10.1021/ja807918f). Complexes of histones form the many spools around which eukaryotic cells wind their DNA for packing and control purposes. David G. Norman of the University of Dundee, in Scotland, and coworkers measured distances spanning the spools by using an EPR technique known as PELDOR, or pulsed electron double resonance. The method permits measurement of distances between nitroxide spin-label pairs installed at various places on the histone spool. Ranging from 59 to 70 Å, the distances Norman’s team measured are among the longest PELDOR measurements ever made on a biological system. Crystallography has yielded static pictures of histone spools with and without DNA, but PELDOR measurements could be used to reveal how DNA-threaded histone spools are assembled and accessed by other cell components, Norman says. More generally, the work demonstrates that PELDOR is a “very powerful technique to characterize structure and functional changes in biomacromolecular complexes,” says Olav Schiemann, an EPR expert at the University of St. Andrews, in Scotland.


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.