Probing Slow Chemical Exchange at Carbonyl Sites in Proteins by Chemical Exchange Saturation Transfer NMR Spectroscopy

Abstract

Seeing the invisible: A 13CO NMR chemical exchange saturation transfer (CEST) experiment for the study of “invisible” excited protein states with lifetimes on the order of 5–50 ms has been developed. The 13CO chemical shifts together with those obtained from fits of 15N CEST profiles establish that the A39G FF domain folds via a similar compact intermediate (I) as the wild-type protein (F and U=native and unfolded states). As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.