Linkers are critical components of fusion proteins, as they physically separate individual domains to enable each to fold and retain function. The role of peptide linker properties was investigated for fusions of a leucine zipper immobilization domain (Z(E)) to a chimeric amine dehydrogenase (AmDH) or a formate dehydrogenase (cbFDH). A linker library was developed, which varied in length, orientation, and proline content, as a way to vary stiffness. Fusion proteins were characterized by melting temperature, immobilization ability, cofactor binding, and kinetic activity. The best linker candidate for each enzyme was tested in a dual-functionality assay, where enzymatic activity of fusions immobilized in protein-inorganic supraparticles was greater than 80% after washing. The best linker for AmDH was completely different than that for cbFDH. This work highlights the need to experimentally assess linker properties in the design of new fusion proteins and provides a linker library for this purpose. (C) 2018 American Institute of Chemical Engineers