Conjugated polymer-based ratiometric fluorescent biosensor for probing the activity of protein-acetylation-related enzymes

摘要

Histone acetylation is a prevalent post-translational modification phenomenon, which is closely related to numerous physiological and pathological processes. In this work, a label-free ratiometric fluorescent biosensing platform based on the change of fluorescence resonance energy transfer (FRET) ratio from polyfluorene derivative (PFP) to fluorescein (FL) via competitive reactions is designed for monitoring histone acetylation. Polycationic substrate peptides could gradually displace PFP in PFP/FL probe, thus resulting in low FRET efficiency. In the presence of histone acetyltransferases (HAT), it can catalyze the acetylation of substrate polypeptide lysine residue, altering the intrinsic charge and diminishing the electrostatic interaction with fluorescein, leading to FRET recovery. Under the optimal conditions, the fabricated assay exhibits a wide linear range of 0.5-500 nM with a detection limit of 0.21 nM for HAT activity detection. The assay was applied to evaluate HAT inhibition by C646, and an IC50 value of 24.3 mu M was obtained. Moreover, the proposed method is applicable for the evaluation of histone deacetylases (HDAC) activity with a linear range from 0.5 to 500 nM and a detection limit of 0.46 nM. The developed protocol could be a promising prospect for clinical diagnosis and drug discovery that are related to HAT/HDAC activity.