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Keywords:

  • carbonyl reductase;
  • coating;
  • hydrophilization;
  • polyether;
  • silicone

Abstract

Industrial use of enzymes requires high activity, stability, and manageability under technical conditions. Therefore, most biocatalysts are immobilized before use, often by physical adsorption onto a solid carrier. However, a major limitation for the technical use of such immobilizates is the insufficient operational stability under process conditions resulting from enzyme leaching and carrier disintegration. Our group demonstrated recently that for lipase-catalyzed esterifications these limitations can be largely overcome by the formation of silCoat biocatalysts, composite materials of carrier-bound enzymes and silicone. Here, we report the successful transformation of this method to the immobilization of carbonyl reductase (CR), an enzyme representing oxidoreductases as a completely different class of biocatalysts. The silCoat biocatalysts cannot be transferred directly to CR because they require an overall hydrophilic surrounding, which opposes the hydrophobicity of silicone. Consequently, the hydrophilization of the material is necessary to achieve reasonable enzyme activity. This was realized by the rational modification of the precursors for silicone formation and applied to increase the leaching stability and mechanical strength of the carrier-bound CR. The resulting HYsilCoat CR had a significantly longer half-life than that obtained through the uncoated preparation; the mechanical stability of an alumina carrier was increased by a factor of 120. This enables the consideration of mechanically unstable but environmentally friendly and/or cheap material as an enzyme carrier for industrial use.