MYELOPEROXIDASE (MPO)

266-6K1

Part of the host defense system of polymorphonuclear leukocytes. It is responsible for microbicidal activity against a wide range of organisms. In the stimulated PMN MPO catalyzes the production of hypohalous acids primarily hypochlorous acid in physiologic situations and other toxic intermediates that greatly enhance PMN microbicidal activity.

Cl- + H2O2 = HOCl + 2 H2O. Cofactor: Binds 1 calcium ion per heterodimer. Cofactor: Binds 1 heme B (iron-protoporphyrin IX) group covalently per heterodimer.

Lysosome.

Belongs to the peroxidase family. XPO subfamily. Summary: Myeloperoxidase (MPO) is a heme protein synthesized during myeloid differentiation that constitutes the major component of neutrophil azurophilic granules. Produced as a single chain precursor myeloperoxidase is subsequently cleaved into a light and heavy chain. The mature myeloperoxidase is a tetramer composed of 2 light chains and 2 heavy chains. This enzyme produces hypohalous acids central to the microbicidal activity of netrophils. [1] Zhang J. Zhu F. Y. Pu Y. P. Yin L. H. Luo J. Wang W. P. and Zhou G. H. Analysis of multiple single nucleotide polymorphisms (SNPs) of myeloperoxidase (MPO) to screen for genetic markers associated with acute leukemia in Chinese Han population[2] Kettle A. J. Anderson R. F. Hampton M. B. and Winterbourn C. C. et al. Reactions of superoxide with myeloperoxidase[3] Taioli E. Benhamou S. Bouchardy C. Cascorbi I. Cajas-Salazar N. Dally H. Fong K. M. Larsen J. E. Le Marchand L. et al. Myeloperoxidase G-463A polymorphism and lung cancer: a HuGE genetic susceptibility to environmental carcinogens pooled analysis[4] Proteasa G. Tahboub Y. R. Galijasevic S. Raushel F. M. and Abu-Soud H. M. Kinetic evidence supports the existence of two halide binding sites that have a distinct impact on the heme iron microenvironment in myeloperoxidase[5] Kaneski C. R. Moore D. F. Ries M. Zirzow G. C. and Schiffmann R. et al. Myeloperoxidase predicts risk of vasculopathic events in hemizgygous males with Fabry disease[6] Morishita K. Kubota N. Asano S. Kaziro Y. Nagata S. Molecular cloning and characterization of cDNA for human myeloperoxidase. [7] Morishita K. Tsuchiya M. Asano S. Kaziro Y. Nagata S. Chromosomal gene structure of human myeloperoxidase and regulation of its expression by granulocyte colony-stimulating factor. [8] Johnson K. R. Nauseef W. M. Care A. Wheelock M. J. Shane S. Hudson S. Koeffler H. P. Selsted M. Miller C. Rovera G. et al. Characterization of cDNA clones for human myeloperoxidase: predicted amino acid sequence and evidence for multiple mRNA species. [9] Johnson K. R. Gemperlein I. Hudson S. Shane S. Rovera G. Complete nucleotide sequence of the human myeloperoxidase gene. [10] Seto P. Hirayu H. Magnusson R. P. Gestautas J. Portmann L. Degroot L. J. Rapoport B. Isolation of a complementary DNA clone for thyroid microsomal antigen. Homology with the gene for thyroid peroxidase.