Introduction
Nat. Chem. Biol. 2, 259–264 (2006); published online 9 April; corrected after print 18 April 2006
In the version of this article initially published, the seventh sentence of the fifth paragraph is incorrect. It should read "Hydrogen atoms for the side chains were also clearly visible when the residues showed low-temperature factors (typically below 8 Å2)." The error has been corrected in the HTML and PDF versions of the article.
