Boosting Catalytic Performance of Cytochrome <i>c</i> through Tailored Carboxymethylation in Covalent Organic Frameworks
Lunlun Shi, Xiupeng Chen, Aitao Li, Xiaoling Wu, Xian Kong, Hongming Lou, Zhixian Li
Abstract
Covalent organic frameworks (COFs) offer a promising platform for enzyme immobilization due to their abundant and chemically modifiable functional groups alongside finely tunable pore structures. Utilizing carboxymethylation, we successfully tailored the microenvironment of COFs and subsequently immobilized the enzyme via adsorption. This strategic modification induces a localized reduction in pH within the COF, significantly enhancing the enzyme’s catalytic activity. Notably, the relative activity of Cyt c @ cm COF-TATP attained 134.8% of its free counterpart, and its catalytic efficiency ( k cat / K M ) reached 278% relative to the free Cyt c . MD simulations indicate that the heightened enzyme activity and stability at low pH for Cyt c @ cm COF-TATP are related to a more stable backbone framework and active site. Additionally, a more compact packing within the active site side chains may also contribute to these favorable characteristics. Furthermore, the intrinsic photocatalytic capability of cm COF-TATP complemented the Cyt c catalysis, yielding a relative activity of 165.7% under the conditions of lighting. Impressively, the enzyme demonstrated enhanced stability, preserving 83.7% activity after six cycles, and exhibited elevated solvent tolerance and pH robustness compared to the free enzyme.