Guanidinium-Induced Denaturation by Breaking of Salt Bridges.
Despite its wide use as a denaturant, the mechanism by which guanidinium (Gdm(+) ) induces protein unfolding remains largely unclear. Herein, we show evidence that Gdm(+) can induce denaturation by disrupting salt bridges that stabilize the folded conformation. We study the Gdm(+) -induced denaturation of a series of peptides containing Arg/Glu and Lys/Glu salt bridges that either stabilize or destabilize the folded conformation. The peptides containing stabilizing salt bridges are found to be denatured much more efficiently by Gdm(+) than the peptides containing destabilizing salt bridges. Complementary 2D-infrared measurements suggest a denaturation mechanism in which Gdm(+) binds to side-chain carboxylate groups involved in salt bridges.
Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park, 904, 1098 XH Amsterdam (The Netherlands).
Heleen
H
Meuzelaar
Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park, 904, 1098 XH Amsterdam (The Netherlands).
Matthijs R
MR
Panman
Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park, 904, 1098 XH Amsterdam (The Netherlands). s.woutersen@uva.nl.
Sander
S
Woutersen
denaturation; guanidinium; protein folding; two-dimensional infrared spectroscopy