Volume 89 Issue 41 | p. 41 | Concentrates
Issue Date: October 10, 2011

Mass Spec Maps Disordered Proteins

Isotope-exchange technique requires little sample to probe ordering transition
Department: Science & Technology
News Channels: Analytical SCENE, Biological SCENE
Keywords: intrinsically disordered proteins, H/D exchange
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Intrinsically disordered proteins CBP (red) and ACTR (blue) fold into a structured complex.
Credit: Biochemistry
Intrinsically disordered proteins CBP (red) and ACTR (blue) fold into a structured complex.
 
Intrinsically disordered proteins CBP (red) and ACTR (blue) fold into a structured complex.
Credit: Biochemistry

Amide hydrogen/deuterium exchange mass spectrometry (H/D-MS), a technique that reveals which protein residues are flexible or exposed to solvent, is an effective tool for mapping the unstructured regions of intrinsically disordered proteins (IDPs) and their transitions to well-folded forms in complexes, researchers report (Biochemistry, DOI: 10.1021/bi200875p). For measuring H/D exchange, mass spectrometry requires less material than other methods such as nuclear magnetic resonance. IDPs are floppy proteins that lack a structured conformation. They often perform functions that require protein-protein interactions, such as signaling. David D. Weis and coworkers at the University of Kansas used H/D-MS to monitor the interaction of two well-characterized IDPs—an unstructured protein called ACTR and a molten globular protein called CBP—as they form a well-folded complex. Most parts of ACTR exchange at rates consistent with unstructured proteins, but residual structure was detected in the parts that form helices in the complex. In contrast, CBP is moderately protected against exchange along its entire length, indicating that it is transiently unstructured. When the two proteins come together, H/D-MS can be used to identify regions involved in binding and folding of the complex.

 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society

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