Plug-and-play functionalization of protein-polymer conjugates for tunable catalysis enabled by genitically encoded "click" chemistry

Protein-polymer conjugates have been widely fabricated and used in many areas across biotechnology and medicine. However, their functions and applications are often limited due to the selected and unchangeable proteins and polymers in the conjugates. To address this constraint, here, we design and fabricate protein-polymer conjugates as generic materials that can be postfunctionalized in a plug-and-play means for tunable catalysis. The key idea is to use genetically encoded "click"chemistry (i.e., SpyTag/SpyCatcher) to functionalize premade conjugates with versatile catalytic moieties. This process can protect the function/activity of ligated moieties from exposure to harsh chemical reactions. To enable easy recyclability, the conjugates are encapsulated in hydrogels before the "click"reaction. Using a biocatalyst and a nanocatalyst as models, we demonstrate the success of using two functionalized hydrogels for efficient catalytic reactions. In addition, the two catalysts can be coupled to perform a two-step artificial chemoenzymatic cascade reaction. Notably, the hydrogel-based catalytic materials allow for easy recovery and reuse for multiple cycles. We anticipate that our strategy will help create easy-to-use materials for catalysis and chemical (bio)transformations.