Nitrilotriacetic Acid Functionalized Microgels for Efficient Immobilization of Hyaluronan Synthase

Enzymes play a vital role in synthesizing complex biological molecules like hyaluronic acid (HA). Immobilizing enzymes on support materials is essential for their efficient use and reuse in multiple cycles. Microgels, composed of cross–linked, highly swollen polymer networks, are ideal for enzyme uptake owing to their high porosity. This study demonstrates the immobilization of His₆-tagged hyaluronan synthase from Pasteurella multocida (PmHAS) onto nitrilotriacetic acid functionalized microgels using different bivalent ions (Ni²⁺, Co²⁺, Mn²⁺, Mg²⁺, and Fe²⁺) via metal affinity binding. The results indicate that using Ni²⁺ yields the microgels with the highest enzyme uptake and HA formation. The immobilized PmHAS enables repetitive enzymatic production, producing high molecular weight HAs with decreasing dispersities in each step. Furthermore, the highest reported yield of HA with high molecular weight for immobilized PmHAS is achieved. This system establishes a foundation for continuous HA formation, with future works potentially enhancing PmHAS stability through protein engineering.