Crowding and confinement effects on enzyme stability in mesoporous silicas

Int J Biol Macromol. 2020 Feb 1;144:118-126. doi: 10.1016/j.ijbiomac.2019.12.034. Epub 2019 Dec 5.

Abstract

To understand the protein functions within a cell, where proteins exist in an extremely crowded and confined state, various modeling and experimental methods have been proposed. Here, we propose a new experimental approach to modulate the macromolecular crowding and/or confinement effects by using mesoporous silicas with two different pore structures. SBA-15 and MSU-F with linear and mesocellular pore structures, respectively, were used to adsorb a model enzyme, glucose oxidase (GOx), in various concentrations ranging from 3 to 430 mg ml-1. The concentration of adsorbed GOx in the mesopores, representing the degree of crowding, showed a good correlation with thermal enzyme stability. Interestingly, the increase of thermal stability as a function of macromolecular crowding showed different correlations depending on the pore structure of mesoporous silicas. It represents that combination of crowding and confinement effects can promote different microenvironments for enzyme molecules, while mesoporous silicas can impose controlled crowding and confinement effects on enzymes due to their uniform and tunable pore structures. It is anticipated that this new and simple approach can provide a tool to elucidate crowding and confinement effects on the protein functions, including its stability in vivo, because the mesopore environments could mimic the real macromolecular cell system under crowding.

Keywords: Confinement effect; Crowding effect; Mesoporous silicas.

MeSH terms

  • Adsorption
  • Aspergillus niger / enzymology
  • Calorimetry, Differential Scanning
  • Dynamic Light Scattering
  • Enzyme Stability
  • Fluorescence
  • Glucose Oxidase / chemistry
  • Glucose Oxidase / metabolism*
  • Macromolecular Substances / chemistry*
  • Porosity
  • Protein Folding
  • Silicon Dioxide / chemistry*
  • Temperature

Substances

  • Macromolecular Substances
  • SBA-15
  • Silicon Dioxide
  • Glucose Oxidase