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

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 firefly luciferase with chiral carbon quantum dots containing l and d-tryptophan constituent (l/d-Trp-CQDs) was investigated. Both the CQDs increased 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 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.