Chirality governs the structure and activity changes of Photinus pyralis firefly luciferase induced by carbon quantum dots

Abstract

Nanobiocatalysis is a novel area integrating various advantages of nanotechnology and enzymatic catalysis. However, great efforts are still needed to fully understand the interactions between nanostructures and enzymes. The biological properties of nano-hybrid enzymes greatly depend on the size and chemical properties of their nano element. However, the impact of nanostructure chirality on the structure/function of the enzymes has not yet been fully investigated. In this study, using experimental and computational approaches, the interaction of Photinus pyralis firefly luciferase with chiral carbon quantum dots containing L and D-tryptophan constituent (L/D-Trp–CQDs) was investigated. Both the CQDs increased K_m of the enzyme for luciferin and resulted in the loss of luciferase activity dose-dependently with more profound effects for D-Trp–CQDs. D-Trp–CQD treatment had significantly increased K_m of the enzyme for ATP (3.5 fold) compared to the untreated enzyme. The changes in the secondary structure of luciferase upon interaction with D-Trp–CQDs were more drastic compared to L-Trp–CQDs, as determined by circular dichroism spectroscopy. Molecular dynamic simulation further confirmed higher conformational changes of luciferase induced by D-Trp–CQDs compared to L-Trp–CQDs. D-Trp–CQD has led to conformational changes of several amino acids involved in the active site, substrate binding site and the flexible loop of luciferase (352–359 residues) that governs the activity of luciferase.