Myeloperoxidase Chlorination and Peroxidation Inhibitor Screening Assay Kit

Myeloperoxidase (MPO) is a crucial enzyme within the heme peroxidase superfamily, predominantly expressed in neutrophils, monocytes, and macrophages. It plays a vital role in innate immunity but is also a significant driver of inflammatory and oxidative stress-related pathologies, making it a promising biomarker and therapeutic target. The development of effective MPO inhibitors is a major focus in pharmaceutical research.

MPO can catalyze two types of redox reactions, including chlorination and peroxidation. The detection principle of peroxidation activity is that the peroxidase in the sample can catalyze the reaction of hydrogen peroxide and non-fluorescence ADHP to obtain the fluorescent product Resorufin (Ex/Em = 535/587 nm), and the fluorescence intensity of Resorufin is directly proportional to the total peroxidase activity in the sample.

In addition, MPO activity can also be detected by chlorination. MPO can catalyze hydrogen peroxide and chloride ions (Cl^-) to produce hypochlorous acid (HClO). HClO can then react with the fluorescent probe APF to produce fluorescein. The resulting fluorescence signal (Ex/Em = 485/525 nm) is proportional to MPO chlorination activity.

This kit provides two distinct, well-established methods for quantifying MPO activity, making it particularly suitable for high-throughput screening of inhibitors.

Figure 1. MPO catalytic mechanism

Figure 2. The IC₅₀ for a typical 4-aminobenzhydrazide inhibition curve is 71.5 nM using the MPO chlorination assay (A) and 95 nM using the MPO peroxidation assay (B).