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Literature summary for 1.11.2.2 extracted from

  • van Dalen, C.J.; Winterbourn, C.C.; Senthilmohan, R.; Kettle, A.J.
    Nitrite as a substrate and inhibitor of myeloperoxidase. Implications for nitration and hypochlorous acid production at sites of inflammation (2000), J. Biol. Chem., 275, 11638-11644.
    View publication on PubMed

Inhibitors

Inhibitors Comment Organism Structure
nitrite nitrite is an excellent inhibitor of the chlorination activity of myeloperoxidase, there is progressive inhibition of enzyme activity with increasing concentration of nitrite up to a maximum of 80%. Upon addition of 100 mM L-tyrosine, enzyme activity is completely restored Homo sapiens

Organism

Organism UniProt Comment Textmining
Homo sapiens
-
-
-

Source Tissue

Source Tissue Comment Organism Textmining
leukocyte
-
Homo sapiens
-
neutrophil
-
Homo sapiens
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
Cl- + H2O2 + H+
-
Homo sapiens HClO + H2O
-
?
additional information in the presence of physiological concentrations of nitrite and chloride, myeloperoxidase catalyzes little nitration of tyrosyl residues in a heptapeptide. However, the efficiency of nitration is enhanced at least 4fold by free tyrosine. Myeloperoxidase oxidizes free tyrosine to tyrosyl radicals that exchange with tyrosyl residues in peptides. These peptide radicals then couple with nitrogen dioxide to form 3-nitrotyrosyl residues Homo sapiens ?
-
?
nitrite + L-tyrosine + H2O2 + H+ poor substrate for myeloperoxidase, but free tyrosine facilitates nitration of tyrosyl residues by acting as a cosubstrate in the reaction Homo sapiens ?
-
?
thiocyanate + H2O2 + H+
-
Homo sapiens ?
-
?

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
0.7
-
nitrite at 21°C in 50 mM sodium phosphate buffer, pH 7.4 Homo sapiens
28.5
-
Cl- at 21°C in 50 mM sodium phosphate buffer, pH 7.4 Homo sapiens
30.5
-
thiocyanate at 21°C in 50 mM sodium phosphate buffer, pH 7.4 Homo sapiens

Cofactor

Cofactor Comment Organism Structure
heme
-
Homo sapiens

IC50 Value

IC50 Value IC50 Value Maximum Comment Organism Inhibitor Structure
0.0013
-
at 21°C in 50 mM sodium phosphate buffer, pH 7.4 Homo sapiens nitrite

General Information

General Information Comment Organism
physiological function at sites of inflammation myeloperoxidase will nitrate proteins, even though nitrite is a poor substrate, because the co-substrate tyrosine will be available to facilitate the reaction Homo sapiens