Abstract
The identification of new strategies to improve the stability of proteins is of utmost importance for a number of applications, from biosensing to biocatalysis. Metal-organic frameworks (MOFs) have been shown as a versatile host platform for the immobilization of proteins, with the potential to protect proteins in harsh conditions. In this work, a new thermostable luciferase mutant has been selected as a bioluminescent protein model to investigate the suitability of MOFs to improve its stability and prompt its applications in real-world applications, for example, ATP detection in portable systems. The luciferase has been immobilized onto zeolitic imidazolate framework-8 (ZIF-8) to obtain a bioluminescent biocomposite with enhanced performance. The biocomposite ZIF-8@luc has been characterized in harsh conditions (e.g., high temperature, non-native pH, etc.). Bioluminescence properties confirmed that MOF enhanced the luciferase stability at acidic pH, in the presence of organic solvents, and at -20 °C. To assess the feasibility of this approach, the recyclability, storage stability, precision, and Michaelis-Menten constants (K(m)) for ATP and d-luciferin have been also evaluated. As a proof of principle, the suitability for ATP detection was investigated and the biocomposite outperformed the free enzyme in the same experimental conditions, achieving a limit of detection for ATP down to 0.2 fmol.