Enzyme stabilization by covalent binding in nanoporous sol‐gel glass for nonaqueous biocatalysis

Abstract

A unique nanoporous sol-gel glass possessing a highly ordered porous structure (with a pore size of 153 A in diameter) was examined for use as a support material for enzyme immobilization. A model enzyme, alpha-chymotrypsin, was efficiently bound onto the glass via a bifunctional ligand, trimethoxysilylpropanal, with an active enzyme loading of 0.54 wt%. The glass-bound chymotrypsin exhibited greatly enhanced stability both in aqueous solution and organic solvents. The half-life of the glass-bound alpha-chymotrypsin was >1000-fold higher than that of the native enzyme, as measured either in aqueous buffer or anhydrous methanol. The enhanced stability in methanol, which excludes the possibility of enzyme autolysis, particularly reflected that the covalent binding provides effective protection against enzyme inactivation caused by structural denaturation. In addition, the activity of the immobilized alpha-chymotrypsin was also much higher than that of the native enzyme in various organic solvents. From these results, it appears that the glass-enzyme complex developed in the present work can be used as a high-performance biocatalyst for various chemical processing applications, particularly in organic media. Published by John Wiley & Sons

Immobilization of His-tagged recombinant xylanase fromPenicillium occitanison Nickel-chelate Eupergit C for increasing digestibility of poultry feed

“…25 The restricted interaction between the immobilized enzyme molecules could also be responsible for retaining the enzyme activity at higher temperatures. 26 Enhanced stability of xylanase at higher temperature is likely to increase its suitability for industrial application. 27 The rate of heat inactivation of immobilized enzyme was investigated in the temperature range between 50 °C and 75 °C.…”

Inorganic nanomaterial-based biocatalysts

“…Enzyme immobilization to inorganic nanomaterials may reduce these risks due to endow physical stability to intrinsic enzyme structure (55,61). In many studies, immobilized enzymes were observed more enhanced stability against high temperature (55,62,63), broad pH range (63) or harsh shaking (64) than their free counterparts. Moreover, proper surface modification can help supporting materials to increase enzyme stability.…”

“…Therefore, it suggest that ionic liquids supported to surface of magnetic nanoparticles could preserve the compact conformation of immobilized lipase at a tough conditions such as high temperature (66). Inorganic nanomaterials also permit stability of enzymes placed in nonaqueous environments that is the limiting factor for industrial application (55). The nanoporous-glass immobilized chymotrypsin exhibited greatly enhanced stability both in aqueous solution and organic solvents.…”

Modification of Mesoporous Silicates for Immobilization of Enzymes

“…This approach, as with any crosslinking approach, eliminates the possibility of leaching of the enzyme and can confer increased stability on the immobilized enzyme. For example, α-chymotrypsin supported on various mesoporous silicates functionalised with trimethoxysilylproponal displayed a half-life greater than 1000 fold of that of the native enzyme in aqueous and organic media [41]. However, the conditions employed and/or possible conformation changes to the enzyme can affect the catalytic activity due to the rather indiscriminate means of cross linking the enzyme and MPS.…”