Electrochemical analysis of abscisic acid based on cytochrome P450 707A3

Cytochrome P450 707A3 (CYP707A3) from Arabidopsis thaliana is responsible for catalyzing hydroxylation of abscisic acid (ABA). In this study, the electrochemical analysis of ABA catalyzed by CYP707A3 protein were investigated. Direct electrochemical analysis of Fe³⁺/Fe²⁺ redox peaks in CYP707A3 was performed at a pyrolytic graphite electrode with a redox potential of approximately −0.5 V in an oxygen-free phosphate-buffered solution (PBS, pH 7.0). Under aerobic conditions, with the addition of ABA, the electrode continuously supplied electrons to the iron porphyrin in CYP707A3 protein, resulting in a continuous increase in the reduction peak current. The relationship between the change in current and the concentration of ABA exhibited typical characteristics of the Michaelis-Menten kinetic mechanism, and the apparent Michaelis constant (K_mapp) was calculated to be 77.08 nmol/L. The biosensor demonstrated a linear response to ABA within the range of 5 nM to 30 nM with a detection limit (LOD) of 4.85 nM (S/N = 3). The biosensor demonstrated high sensitivity, excellent reproducibility and good selectivity. It was applied to measure ABA content in the rice leaves under normal condition and drought stress, respectively.