Adsorption of an Endoglucanase from the HyperthermophilicPyrococcusfuriosuson Hydrophobic (Polystyrene) and Hydrophilic (Silica) Surfaces Increases Protein Heat Stability

Abstract

The interaction of an endoglucanase from the hyperthermophilic microorganism Pyrococcus furiosus with two types of surfaces, that is, hydrophobic polystyrene and hydrophilic silica, was investigated, and the adsorption isotherms were determined. The adsorbed hyperthermostable enzyme did not undergo loss of biological activity. A model was proposed for the mechanism of interaction of the enzyme with the surface based on the shape of the adsorption isotherm, the morphological characteristics of the enzyme, and the thermodynamic parameters of the system. The enzyme was irreversibly immobilized at the solid/liquid interface even at high temperatures, and most interestingly, it acquired further heat stabilization upon adsorption. The denaturation temperature increased from 108 degrees C in solution to 116 degrees C upon adsorption on hydrophilic silica particles. Adsorption on the hydrophobic polystyrene surface even shifted the denaturation temperature to 135 degrees C, the most extreme experimentally determined protein denaturation temperature ever reported. Maintenance of the biological function particularly at high temperatures is important for the development of solid substrate immobilized enzymes for applications in biocatalysis and biotechnology. This also presents an additional stabilization mechanism employed by nature where the extracellular hyperthermostable enzyme remains folded and active at the extreme temperatures of its natural environment by adsorption on the surface of rocks and other materials appearing in the surroundings of the microorganism.

Evaluation of nanoparticle‐immobilized cellulase for improved ethanol yield in simultaneous saccharification and fermentation reactions

“…Also, the same mass of enzyme was used in the solution and immobilized enzyme reactions, but this does not mean that same amount of enzyme is available to participate in the catalysis. Enzyme immobilization results in a random orientation of the physisorbed enzyme on the silica substrate, and this leads to some inactive enzyme due to buried or inaccessible active sites (Koutsopoulos et al, 2004). There may also be steric constraints on the enzyme's active site by neighboring enzyme, but this should be limited in this data by the use of $0.5 monolayer of protein, as described above.…”

“…Immobilization of an endoglucanase from the hyperthermophilic Pyrococcus furiosus was found to stabilize the enzyme against denaturation with increasing reaction temperature (Koutsopoulos et al, 2004). Gole et al (2001) reported increased enzymatic stability against shifts in pH and temperature for an immobilized fungal endoglucanase.…”

The Preparation and Enzyme Immobilization of Hydrophobic Polysiloxane Supports

“…[14] Thermodynamically, the extent of enzyme immobilization (adsorption) is determined by the Gibbs energy of adsorption, which, at a certain temperature, depends on the enthalpy and the entropy of adsorption. [28,29] Enthalpic driving forces include attractive or repulsive Coulombic forces and attractive van der Waals interactions between biomolecules and the interface. Entropic contributions to the Gibbs energy of adsorption may result from hydrophobic dehydration and conformational changes in the enzyme molecules.…”

“…Previous studies have indicated that, irrespective of conformational stability arguments, proteins in aqueous solutions have the propensity to adsorb on hydrophobic surfaces. [14,28] Enzymatic Activity Tests…”

Immobilization of Candida antarctica lipase B on Polystyrene Nanoparticles

“…[14] Therefore, immobilization research has largely focused on matrix selection and on optimizing immobilization conditions. [15][16][17][18] For example, work has addressed support surface hydrophobicity/hydrophobocity [19,20,21] and 3 enzyme solution pH. [17,22,23] These parameters have large influence on the total amount of enzyme loading and enzyme-catalyst activity.…”