title: Inactivation of myeloperoxidase by benzoic acid hydrazide.
abstract: Myeloperoxidase (MPO) is expressed by myeloid cells for the purpose of catalyzing the formation of hypochlorous acid, from chloride ions and reaction with a hydrogen peroxide-charged heme covalently bound to the enzyme. Most peroxidase enzymes both plant and mammalian are inhibited by benzoic acid hydrazide (BAH)-containing compounds, but the mechanism underlying MPO inhibition by BAH compounds is largely unknown. Recently, we reported MPO inhibition by BAH and 4-(trifluoromethyl)-BAH was due to hydrolysis of the ester bond between MPO heavy chain glutamate 242 ((HC)Glu(242)) residue and the heme pyrrole A ring, freeing the heme linked light chain MPO subunit from the larger remaining heavy chain portion. Here we probed the structure and function relationship behind this ester bond cleavage using a panel of BAH analogs to gain insight into the constraints imposed by the MPO active site and channel leading to the buried protoporphyrin IX ring. In addition, we show evidence that destruction of the heme ring does not occur by tracking the heme prosthetic group and provide evidence that the mechanism of hydrolysis follows a potential attack of the (HC)Glu(242) carbonyl leading to a rearrangement causing the release of the vinyl-sulfonium linkage between (HC)Met(243) and the pyrrole A ring.
authors: Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, United States.
authors: Jiansheng
authors: J
authors: Huang
authors: Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, United States.
authors: Forrest
authors: F
authors: Smith
authors: Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
authors: Jennifer R
authors: JR
authors: Panizzi
authors: Department of Chemistry and Biochemistry, College of Science and Mathematics, Auburn University, Auburn, AL 36849, United States.
authors: Douglas C
authors: DC
authors: Goodwin
authors: Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, United States. Electronic address: panizzi@auburn.edu.
authors: Peter
authors: P
authors: Panizzi
mesh_terms: D000595:Amino Acid Sequence; D000814:Aniline Compounds / Q000737:chemistry*; D000818:Animals; D019817:Benzoic Acid / Q000737:chemistry; D002232:Carbocyanines / Q000737:chemistry; D020134:Catalytic Domain; D002417:Cattle; D004583:Electrons; D004791:Enzyme Inhibitors / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D018698:Glutamic Acid / Q000737:chemistry; D006418:Heme / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007249:Inflammation; D008239:Lysine / Q000737:chemistry; D013058:Mass Spectrometry; D008715:Methionine / Q000737:chemistry; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000201:enzymology; D010100:Oxygen / Q000737:chemistry; D009195:Peroxidase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D000814:Aniline Compounds; D002232:Carbocyanines; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D005609:Free Radicals; C085321:cyanine dye 5; D018698:Glutamic Acid; D006418:Heme; C034343:4-aminobenzhydrazide; D019817:Benzoic Acid; D008715:Methionine; D006861:Hydrogen Peroxide; D009195:Peroxidase; D008239:Lysine; D010100:Oxygen
keywords: Benzoic acid hydrazide; Inflammation; Myeloperoxidase