The definition of myeloperoxidase
Myeloperoxidase (MPO), also known as peroxidase, is a hemoglobin heme protease, is a member of the heme peroxidase superfamily. , Present in the myeloid cells (mainly neutrophils and mononuclear cells) of the aniline blue particles is a specific marker of myeloid cells, with the depth of the Myeloperoxidase(MPO) study, it was found thatMyeloperoxidase(MPO) gene polymorphism led to the individual The susceptibility to some diseases is closely related to the occurrence and development of various diseases in human. Therefore, more and more scholars pay more attention to it.
The structure of myeloperoxidase
Myeloperoxidase(MPO) is a heme-containing heme protease secreted by neutrophils, monocytes and macrophages from certain tissues and is a member of the heme-peroxidase superfamily . Myeloperoxidase(MPO) is a metabolic enzyme. Each enzyme molecule has two ferritin groups, and the paramagnetic resonance spectrum indicates that the iron in the heme is in the formyl heme fraction. In the discovery of Concord Rock, Myeloperoxidase synthesis is granulocytes into the circulation before the synthesis and storage in the bone marrow within the particles, external stimuli can lead to neutrophil aggregation, the release of myeloperoxidase (MPO). In mature granulocytes, Myeloperoxidase(MPO) is the most abundant glycoprotein, accounting for about 5% of the total protein content of polymorphonuclear neutrophils (PMNs) in peripheral blood. 95% of MPO in blood is from PMNs. Myeloperoxidase (MPO) molecular weight of 150 × 103, is composed of two subunits polymer dimer, each subunit by a heavy chain (α chain, relative molecular mass of about 60 × 103) and a light chain ( Β chain, the relative molecular mass of about 15 × 103) constituted. The two subunits are linked by a disulfide bond at the alpha chain. The heavy chain has a ferroporphyrin group, indicating that MPO is iron-dependent. Myeloperoxidase(MPO) exists in myeloid cells in three subtypes, respectively Myeloperoxidase(MPO) Ⅰ, Ⅱ, Ⅲ. The difference of the three subtypes is different. The differences of the three subtypes are unclear, and need to be further studied. Keywords: heavy chain, light chain, light chain, molecular weight, hydrophilicity Clinical detection ofELISA. This is a screening method, ELISA quantitative detection.
Myeloperoxidase gene and its polymorphism
The human myeloperoxidase gene is located on chromosome 17q23q24 and contains 12 exons and 11 introns, about 14 638 bp in length. The gene that regulates gene expression is a growth factor. MPO mRNA expression in promyelocytic cells was the highest, followed by primitive granulocytes, immature and primitive monocytes; when the cell differentiation to maturity, Myeloperoxidase(MPO) gene expression levels decreased rapidly. It is known that the MPO gene first expresses a precursor protein with a relative molecular mass of 89×103, which has been post-translationally processed and cleaved into α and β subunits and then polymerized into mature MPO molecules. On the sugar chain, and finally the formation of functional MPO. MPO gene expression in the process of the existence of defects, resulting in MPO gene DNA sequence changes, affecting its vitality. Polymorphism of MPO gene affects the transcription and expression of the gene, which has a certain influence on the susceptibility of the disease. Chevrier, and unionluck found that V53F, A332V, I642L and IVS11 2A→C4 new polymorphic loci in exon 11 and promoter region, and their roles and functions need further study. Piedrafita, unionluck and other studies found that the disease-related sites are 5: 463G/A, R569W, Y173C, M251T and exon 9 base deletion. The most studied is the mutation of the 463rd nucleotide G/A of the promoter region of the MPO gene, which is located in the cis-acting element of SP1 transcription factor recognition binding, which contains four Alu repeats. Mutation of G/A resulted in disappearance of the SP1 transcription factor binding site located in the Alu response element, resulting in a significant decrease in MPO transcription level. Unionluck has also reported that codon 569 of exon 10 has C replaced by T, causing CGG→TGG, leading to hereditary MPO-deficient disease. There are also reports of the presence of G at the 129 site of MPO gene substitution by A, the MPO gene expression levels were significantly reduced. In addition, according to the literature, MPO gene 463A allele and some cancer risk reduction.
The biological effects of myeloperoxidase
Myeloperoxidase (MPO) is a functional marker and activation marker of neutrophils. The level and activity of neutrophils represent the function and activity of neutrophil polymorphonuclear leukocytes (PMNs). The activity of purified human MPO was 25 ~ 35IU/mg, the water-solubility was good, the enzyme was inhibited when the substrate H2O2 concentration was more than 0.8mmol, the optimum pH of the enzyme reaction was 4.5~5.5, the enzyme was inactivated when pH≥10, . MPO's main function is to kill microorganisms in the phagocytic cells, the use of hydrogen peroxide and chloride ions to produce hypochlorite, and the formation of free radicals with oxidative capacity. Constitute the MPO-H2O2-halogen system. It is found that Myeloperoxidase (MPO) can not only kill the microorganisms that are engulfed in the cells, but also release them to the cells and destroy many kinds of target substances, such as tumor cells, platelets, NK cells, protozoa and toxins. And so play a role. However, under certain conditions, the Myeloperoxidase (MPO) catalyzes the reaction to form excess oxidants (HOCl, 3-chlorotyrosine, tyrosyl, nitrotyrosine, etc.) which, when exceeded by the local antioxidant, Stress and oxidative tissue damage. Myeloperoxidase (MPO) is also involved in the regulation of inflammatory response in many processes, MPO-deficient neutrophils due to excessive injection of inflammatory sites and oxidative reaction, a large number of superoxide and oxide formation, resulting in inflammation of the site of tissue damage. In addition, there are scholars of Concord Rock found that Myeloperoxidase (MPO) can be combined with DNA to form a solid complex to effectively protect the DNA to prevent damage in the oxidation process to ensure the normal differentiation and maturation of myeloid cells and function. Neutrophils are granular white blood cells that play an important role in host defense and phagocytosis of infectious bacteria. The textbook model for neutrophil function is such that the toxic peroxides are released into the vesicles containing the ingested microorganisms, followed by the myeloperoxidase-catalyzed halogenation.
The biological principle of myeloperoxidase
The 96-well microtiter plate coated anti-MPO antibody binds to the MPO antigen in the analyte and standard, and the horseradish peroxidase-labeled anti-MPO antibody binds to the other sites of the antigen to form a sandwich antigen antibody Complexes, the catalytic substrate TMB into blue material, after the termination of yellow, the color depth of the sample and the Myeloperoxidase (MPO) antigen concentration. The absorption peak at 450nm wavelength, by ELISA reader to detect the absorbance (OD value). The concentration of the analyte is calculated from the OD value.
The significance of myeloperoxidase
Myeloperoxidase(MPO) may independently predict the future risk of cardiovascular disease in healthy individuals, independent of C-reactive protein and other inflammatory markers. The New England Journal of Medicine published a study in 2003 that predicted the probability of a cardiovascular event in 30 to 6 months by measuring MPO levels in 604 patients with chest pain. If cTnT was detected alone, only 54% of patients were predicted, and the probability of detecting MPO was increased to 84.5%.