2011/10/20 by Samuel S. Cho, Cho, Samuel S., Govardhan Reddy +5
Biochemistry, Genetics and Molecular Biology · Chemistry · Materials Science · Physics and Astronomy · #Biological Physics (physics.bio-ph) #Biomolecules (q-bio.BM) #Enzyme Structure and Function #FOS: Biological sciences #FOS: Physical sciences #Mass Spectrometry Techniques and Applications #Protein Structure and Dynamics #Statistical Mechanics (cond-mat.stat-mech) #cond-mat.stat-mech #physics.bio-ph #q-bio.BM
paper · pdf · doi:10.48550/arxiv.1110.4605
27 pages, 10 figures
arxiv created 2011/10/20 · openalex publication_date 2011/10/20 · arxiv updated 2011/10/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
To understand the mechanism of trimethylamine N-oxide (TMAO) induced stabilization of folded protein states, we systematically investigated the action of TMAO on several model dipeptides (Leucine, L2, Serine, S2, Glutamine, Q2, Lysine, K2, and Glycine, G2) in order to elucidate the effect of residue-specific TMAO interactions on small fragments of solvent-exposed conformations of the denatured states of proteins. We find that TMAO preferentially hydrogen bonds with the exposed dipeptide backbone, but generally not with nonpolar or polar side chains. However, interactions with the positively charged Lys are substantially greater than with the backbone. The dipeptide G2, is a useful model of pure amide backbone, interacts with TMAO by forming a hydrogen bond between the amide nitrogen and the oxygen in TMAO. In contrast, TMAO is depleted from the protein backbone in the hexapeptide G6, which shows that the length of the polypeptide chain is relevant in aqueous TMAO solutions. These simulations lead to the hypothesis that TMAO-induced stabilization of proteins and peptides is a consequence of depletion of the solute from the protein surface provided intramolecular interactions are more favorable than those between TMAO and the backbone. To test our hypothesis we performed additional simulations of the action of TMAO on an intrinsically disordered Aβ16-22 (KLVFFAE) monomer. In the absence of TMAO Aβ16-22 is a disordered random coil. However, in aqueous TMAO solution Aβ16-22 monomer samples compact conformations. A transition from random coil to α-helical secondary structure is observed at high TMAO concentrations. Our work highlights the potential similarities between the action of TMAO on long polypeptide chains and entropic stabilization of proteins in a crowded environment due to excluded volume interactions. In this sense TMAO is a nano-crowding particle.