Designing an ecofriendly catalyst for a sustainable use of water resources

The printing and dyeing industry is one of the most polluting (∼20% of global clean water pollution), water-consuming and energy-wasting sectors in the manufacturing field, highlighting the need to find green catalysts to improve its sustainability. Herein, a novel artificial green catalyst was developed, known as a bifunctional chimeric peptide DNAzyme (bi-CPDzyme), comprising peptide, DNA and hemin moieties. This catalyst displays both catalase (CAT) and peroxidase (POD) activities. The turnover number (k_cat) of the optimized bi-CPDzyme prototype (G-quadruplex-Hemin-HRRHKHRRH) surpasses the natural CAT/POD bifunctional enzyme KatG, and competes with individual CAT and POD enzymes. This remarkable performance is attributed to the strategic combination and incorporation of histidine (H) and arginine (R) residues, which effectively trap hydrogen peroxide (H₂O₂) near the catalytic center via hydrogen bond formation, thus facilitating the generation of the active intermediate compound I, as supported here by theoretical calculations. Significantly, bi-CPDzyme achieves efficient decomposition of bleaching-derived residual H₂O₂ in a water-/energy-saving manner, while degrading dyes from textile industry effluents even in complex real samples, in addition to being easily recyclable and implementable. These findings make bi-CPDzyme a cutting-edge and environmentally friendly catalyst, positioning it at the forefront of advancements towards creating a sustainable society.