Self-assembly of beta-glucosidase and D-glucose-tethering zeolite crystalsinto fibrous aggregates

beta -Glucosidase and D-glucose-tethering micrometer-sized zeolite crystals self-assemble into thin (2-20 mum) and very long (>1 cm) fibrous aggregate s in water. The process proceeds at a faster rate in a buffer solution of p H 4.8 at which the enzymatic activity is highest. The zeolite and enzyme re main intact within the fibrous material. Furthermore, the enzymatic activit y of beta -glucosidase is preserved even after they are kept in water for m ore than 6 months at room temperature. With the zeolite to enzyme weight ra tio of 5, all the zeolite crystals are buried within the round fibrils whic h consist of either a single strand or helical double strands. Upon increas ing the ratio to 10, clusters of unburied zeolite crystals appear on the ex terior of the fibrils, while narrow flat fibers with smooth surfaces are fo rmed upon decreasing the ratio to 2.5. The process is proposed to initiate by the tight binding between the zeolite-bound D-glucose moieties and beta -glucosidase followed by crystallization of the enzyme over the zeolite-bou nd enzyme monolayer. This report thus reveals a novel behavior of beta -glu cosidase and demonstrates an unprecedented phenomenon that an enzyme and it s substrate-tethering inorganic crystals self-assemble into structured aggr egates.