peroxidase Inhibitors

Eosinophil peroxidase, lactoperoxidase, and thyroid peroxidase inhibitors are a class of compounds that interfere with the enzymatic activity of specific peroxidases found in the body. These peroxidases play key roles in physiological processes by catalyzing the oxidation of substrates using hydrogen peroxide as the electron acceptor. Eosinophil peroxidase (EPO) is primarily found in eosinophils, a type of white blood cell involved in immune response and inflammatory reactions. It utilizes hydrogen peroxide and halides (like chloride or bromide) to produce hypohalous acids, which help combat pathogens. Lactoperoxidase (LPO) is found in various secretory fluids such as saliva, milk, and airway secretions, where it serves as an antimicrobial agent by generating reactive oxygen species (ROS). Thyroid peroxidase (TPO) is crucial in the synthesis of thyroid hormones, as it catalyzes the iodination of tyrosine residues on thyroglobulin and the coupling of iodotyrosines to form thyroxine (T4) and triiodothyronine (T3).

Inhibitors of these peroxidases work by blocking their ability to catalyze reactions involving hydrogen peroxide and various substrates. By binding to the active site or altering the enzyme's structure, these inhibitors can effectively reduce or prevent the formation of reactive oxygen or iodine species. This modulation of enzyme activity impacts the normal production of hypohalous acids in immune responses or hormone synthesis in the thyroid gland. Additionally, the presence of these inhibitors can alter local oxidative environments, as they hinder the generation of certain oxidative metabolites. Because EPO, LPO, and TPO share functional similarities in using hydrogen peroxide and organic/inorganic substrates, many inhibitors can target more than one of these peroxidases, though specificity and potency can vary widely depending on the compound structure and mode of action. Understanding the structural characteristics and mechanisms of these inhibitors is crucial for elucidating their biochemical impact on peroxidase-mediated reactions.