ACS_journal of chemical information and modeling


ACS_journal of chemical information and modeling

January 8, 2024

Volume 64, Issue 1

Pages 1-326

Molecular Aggregation Behavior and Microscopic Heterogeneity in Binary Osmolyte–Water Solutions

Osmolytes, small organic compounds, play a key role in modulating the protein stability in aqueous solutions, but the operating mechanism of the osmolyte remains inconclusive. Here, we attempt to clarify the mode of osmolyte action by quantitatively estimating the microheterogeneity of osmolyte–water mixtures with the aid of molecular dynamics simulation, graph theoretical analysis, and spatial distribution measurement in the four osmolyte solutions of trimethylamine-N-oxide (TMAO), tetramethylurea (TMU), dimethyl sulfoxide, and urea. TMAO, acting as a protecting osmolyte, tends to remain isolated with no formation of osmolyte aggregates while preferentially interacting with water, but there is a strong aggregation propensity in the denaturant TMU solution, characterized by favored hydrophobic interactions between TMU molecules. Taken together, the mechanism of osmolyte action on protein stability is proposed as a comprehensive one that encompasses the direct interactions between osmolytes and proteins and indirect interactions through the regulation of water properties in the osmolyte–water mixtures.

  • Jiwon Seo, Ravi Singh
  • Jonghyuk Ryu
  • Jun-Ho Choi

Image created by minjeong Kim / Nanosphere