Combinatorial discovery of reusable noncovalent supports for enzyme immobilization and nonaqueous catalysis

A simple and effective method is described for the preparation of enzyme-containing materials that possess excellent catalytic activity, mechanical strength, and reusability. Uniform spherical beads were produced via the colyophilization of alpha-chymotrypsin with the support materials, leaving the active enzyme entrapped within the porous "ice-templated" support matrix. The composites were assayed for catalytic activity by monitoring a nonaqueous transesterification reaction. The mechanical strength for each composite was measured using a compression assay. Initial screens identified a set of six support materials that contributed favorably to either the enzyme activity or to the mechanical strength of the composite. A design of experiments (DoE) methodology was employed to screen 80 combinations of these six "base" materials. A model representing this formulation space was constructed which could be used to predict both the catalytic activity and mechanical strength with reasonable accuracy for any combination of the six base component materials. This model was used to predict optimized materials with an enzyme activity that was 50 times greater than that of the free enzyme. The model was also used to set a minimum acceptable mechanical stability for these composites, and the resulting materials were shown to be reusable for at least ten reaction cycles.