Screening of 5′-Methylthioadenosine Nucleosidase Enzyme Inhibitors from Traditional Chinese Medicine and Small Molecular Compounds by Capillary Electrophoresis After Enzymatic Reaction at Capillary Inlet

Abstract

A capillary electrophoresis (CE) method was developed for the screening of 5′-methylthioadenosine nucleosidase (MTAN) inhibitors in traditional Chinese drugs and small molecular compounds. In this method, reaction occurred at the capillary inlet during a predetermined waiting period, followed by electrophoretic separation of the reaction substrates and products. Parameters affecting separation efficiency and enzyme activity were evaluated systematically. The optimized conditions were as follows: 30 mM phosphate (pH 3.0) running buffer, 25 kV applied voltage, 20 mM HEPES (pH 6.0) reaction buffer, and 4 min incubation time. Under the optimized conditions, the Michaelis–Menten constant (Km) of MTAN was 3.44 μM, which agreed with the documented data. The proposed method was successfully applied for MTAN inhibitor screening from 21 natural extracts and 8 small molecular compounds. The results demonstrated the practical applicability of the at-inlet reaction-based CE method in screening of MTAN inhibitors from natural products and small molecular compounds.