Trelle, Morten Beck3; Madsen, Jeppe B2; Andreasen, Peter A2; Jørgensen, Thomas J D3
1 Department of Biochemistry and Molecular Biology, Faculty of Science, SDU2 unknown3 Department of Biochemistry and Molecular Biology, Faculty of Science, SDU
The metastability of the native fold makes serpin (serine protease inhibitor) proteins prone to pathological conformational change, often by insertion of an extra β-strand into the central β-sheet A. How this insertion is made possible is a hitherto unresolved question. By the use of advanced hydrogen/deuterium-exchange mass spectrometry (HDX-MS) it is shown that the serpin plasminogen activator inhibitor 1 (PAI-1) transiently unfolds under native condition, on a second-to-minute time scale. The unfolding regions comprise β-strand 5A as well as the underlying hydrophobic core, including β-strand 6B and parts of helices A, B, and C. Based thereon, a mechanism is proposed by which PAI-1 makes transitions through progressively more unfolded states along the reaction coordinate to the inactive, so-called latent form. Our results highlight the profound utility of HDX-MS in detecting sparsely populated, transiently unfolded protein states.
Angewandte Chemie (international Edition), 2014, Vol 53, Issue 37, p. 9751-4
Thrombosis; Protein Folding; Mass Spectrometry; Fibrinolysis