Protein-inorganic calcium-phosphate supraparticles as a robust platform for enzyme co-immobilization

Immobilization of enzymes provides many benefits, including facile separation and recovery of enzymes from reaction mixtures, enhanced stability, and co-localization of multiple enzymes. Calcium-phosphate-protein supraparticles imbued with a leucine zipper binding domain (Z_R ) serve as a modular immobilization platform for enzymes fused to the complementary leucine zipper domain (Z_E ). The zippers provide high-affinity, specific binding, separating enzymatic activity from the binding event. Using fluorescent model proteins (mCherryZ_E and eGFPZ_E ), an amine dehydrogenase (AmDHZ_E ), and a formate dehydrogenase (FDHZ_E ), the efficacy of supraparticles as a biocatalytic solid support was assessed. Supraparticles demonstrated several benefits as an immobilization support, including predictable loading of multiple proteins, structural integrity in a panel of solvents, and the ability to elute and reload proteins without damaging the support. The dual-enzyme reaction successfully converted ketone to amine on supraparticles, highlighting the efficacy of this system.