Related Experiment Video
Updated: Jul 15, 2026

Modification and Functionalization of the Guanidine Group by Tailor-made Precursors
Published on: April 27, 2017
The interaction of guanidinium ions with a model peptide
Philip E Mason1, John W Brady, George W Neilson
1Department of Food Sciences, Stocking Hall, Cornell University, Ithaca, New York, USA.
Abstract:
In addition to promoting unfolded protein states, the denaturants urea and guanidinium (Gdm(+)) accumulate at the surface of folded proteins at subdenaturing concentrations, a phenomenon that correlates with their denaturant activities. The enhanced accumulation of Gdm(+) relative to urea indicates different binding modes, or additional binding sites, for Gdm(+), and we recently proposed potential binding modes to protein functional groups for Gdm(+) based on the determination of the weak hydration properties of this complex cation. Here we describe molecular dynamics simulations of a model helical peptide, melittin, in a 3 M solution of GdmCl, to identify potential interactions with amino-acid side chains in a nondenatured polypeptide surface. The simulations indicate that Gdm(+) can interact with a number of planar amino-acid side chains (Arg, Trp, Gln) in a stacking manner, as well as more weakly with hydrophobic surfaces composed of aliphatic side chains, and that these interactions result in enhanced number densities of Gdm(+) at certain locations on the peptide surface. These observations provide molecular scale insight into the accumulation of Gdm(+) at protein surfaces that has previously been observed experimentally.
Related Concept Videos
GTPases and their Regulation
Large G-proteins, also known...
Activation and Inactivation of G Proteins
G-Protein Gated Ion Channels
Sensory organs,...
Peptide Bonds
G-protein Coupled Receptors

