PerspectiveBiochemistry

Exciting Structures

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Science  10 Sep 2010:
Vol. 329, Issue 5997, pp. 1295-1296
DOI: 10.1126/science.1195571

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Summary

The beautiful images of protein structures that we see in journals and textbooks have contributed immensely to our basic understanding of how proteins fold and function. Yet these structures represent only one state of the protein—typically its most probable “ground state.” Proteins, however, undergo dynamic excursions from their ground states and, much more rarely, morph into entirely different structural forms sometimes referred to as excited states. A growing number of studies suggest that excited states are a ubiquitous feature of biomolecules that may hold the key to unlocking some of the deepest and most poorly understood aspects of catalysis (1), signaling (2), recognition (3), and folding (4). It has proven to be a very daunting task, however, to determine the high-resolution structure of excited proteins using conventional techniques such as nuclear magnetic resonance (NMR) spectroscopy and x-ray crystallography. In part, this is because excited states exist for too little time (less than a millisecond) and in too little abundance (less than 5% of protein molecules). On page 1312 of this issue, Korzhnev et al. (5) outline a general strategy for overcoming these challenges using NMR data and computational methods. Their approach marks the meeting of two research frontiers that have successfully capitalized on the power of observing, in experiments, the “NMR chemical shift,” an important electromagnetic characteristic of atoms in protein molecules.