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Updated: Jul 31, 2026

Submillisecond Conformational Changes in Proteins Resolved by Photothermal Beam Deflection
Published on: February 18, 2014
Millisecond Laue structures of an enzyme-product complex using photocaged substrate analogs
B L Stoddard1, B E Cohen, M Brubaker
1Division of Basic Sciences, Program in Structural Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA. bstoddar@fred.fhcrc.org
Abstract:
The structure of a rate-limited product complex formed during a single initial round of turnover by isocitrate dehydrogenase has been determined. Photolytic liberation of either caged substrate or caged cofactor and Laue X-ray data collection were used to visualize the complex, which has a minimum half-life of approximately 10 milliseconds. The experiment was conducted with three different photoreactive compounds, each possessing a unique mechanism leading to the formation of the enzyme-substrate (ES) complex. Photoreaction efficiency and subsequent substrate affinities and binding rates in the crystal are critical parameters for these experiments. The structure suggests that CO2 dissociation is a rapid event that may help drive product formation, and that small conformational changes may contribute to slow product release.
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