Hyperthermostable cube-shaped assembly in water

Abstract

Proteins in hyperthermophiles exhibit extremely high thermal stability unlike general proteins. These thermostable proteins are stabilized by weak molecular interactions such as hydrogen bonding, charge interactions and van der Waals (vdW) interactions, along with the hydrophobic effect. An in-depth understanding of the stabilization mechanisms will enable us to rationally design artificial molecules with very high thermal stability. Here we show thermally stable supramolecular assemblies composed of six identical amphiphilic molecules having an indented hydrophobic surface, held together by weak intermolecular interactions (vdW and cation-π interactions) and the hydrophobic effect in water. The disassembly temperature of one of the assemblies is over 150°C, which is higher than that of the most hyperthermophilic protein reported to date (PhCutA1). Study of the relationship between the structure of the components and the stability of the assemblies indicates that the hyperthermostability is achieved only if all the weak interactions and the hydrophobic effect work cooperatively.

A Balance between van der Waals and Cation–π Interactions Stabilizes Hydrophobic Assemblies

“…The thermal stability of the BM nanocube was improved by filling the inner void space of the nanocube with hydrophobic molecules . The same effect was observed in the other nanocubes.…”

Polarizability and isotope effects on dispersion interactions in water

“…Molecular design of building blocks. Previously, we reported cube-shaped discrete molecular self-assemblies, i.e., nanocubes, from gear-shaped amphiphiles (GSAs) in water 16,17 . The main driving force of the self-assembly of the nanocubes is the hydrophobic effect, but weak intermolecular interactions such as dispersion 18 and cation-π 19 interactions also significantly contribute to the stability of the nanocubes.…”

“…The main driving force of the self-assembly of the nanocubes is the hydrophobic effect, but weak intermolecular interactions such as dispersion 18 and cation-π 19 interactions also significantly contribute to the stability of the nanocubes. The accumulation of multiple weak interactions give rise to great thermal stability of the nanocubes, which do not disassemble into the monomers at all at even higher temperature than the boiling point of water 17 . These stable nanocubes are attractive for their use towards molecular functions 20,21,22 , but their extremely high stability prevents us from determining the thermodynamic parameters for the self-assembly of the nanocubes to precisely discuss the effect of the weak intermolecular interactions.…”

Supramolecular fluorescence sensor for liquefied petroleum gas

“…The GSA used in this research is a C 2v -symmetric hexaphenylbenzene (HPB) derivative, 1·Cl 2 (Fig. 1a), six molecules of which assemble into a nanocube, [1 6 ] Cl 12 , in water, while 1·Cl 2 retains its monomer state in methanol 12 . Absorption and emission spectra of [1 6 ]Cl 12 and of 1·Cl 2 were measured in water and in methanol, respectively.…”

“…The supramolecular sensor is a 2-nm-sized cubeshaped assembly i.e. nanocube consisting of six molecules of gearshaped amphiphiles (GSAs), which tightly mesh with each other 12 . The nanocube has an~1-nm-sized hydrophobic inner cavity, where several hydrophobic and anionic species are encapsulated to alter the size of the nanocube in an induced-fit manner 13 .…”