Information on EC 1.11.2.2 - myeloperoxidase

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The expected taxonomic range for this enzyme is: Eukaryota

EC NUMBER
COMMENTARY
1.11.2.2
-
RECOMMENDED NAME
GeneOntology No.
myeloperoxidase
-
REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
Cl- + H2O2 + H+ = HClO + H2O
show the reaction diagram
-
-
-
-
SYSTEMATIC NAME
IUBMB Comments
chloride:hydrogen-peroxide oxidoreductase (hypochlorite-forming)
Contains calcium and covalently bound heme (proximal ligand histidine). It is present in phagosomes of neutrophils and monocytes, where the hypochlorite produced is strongly bactericidal. It differs from EC 1.11.1.10 chloride peroxidase in its preference for formation of hypochlorite over the chlorination of organic substrates under physiological conditions (pH 5-8). Hypochlorite in turn forms a number of antimicrobial products (Cl2, chloramines, hydroxyl radical, singlet oxygen). MPO also oxidizes bromide, iodide and thiocyanate. In the absence of halides, it oxidizes phenols and has a moderate peroxygenase activity toward styrene.
SYNONYMS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
donor, hydrogen peroxide oxidoreductase
P05164
-
donor, hydrogen peroxideoxidoreductase
-
-
donor: H202 oxidoreductase
-
-
donor: H202 oxidoreductase
-
-
donor: H2O2 oxidoreductase
-
-
donor:H2O2 oxidoreductase
-
-
donor:H2O2 oxidoreductase
P05164
-
donor:hydrogen peroxide oxidoreductase
-
-
donor:hydrogen-peroxide oxidoreductase
-
-
EC 1.11.1.7
P05164
-
hemi-MPO
-
reductive alkylation converts the normal dimeric enzyme into two protomers, hemi-myeloperoxidase
hemi-myeloperoxidase
-
reductive alkylation converts the normal dimeric enzyme into two protomers, hemi-myeloperoxidase
LPO
-
-
MPO
P05164
-
MPO
P05164
isoform C
myeloperoxidase
-
-
peroxinectin
-
-
properoxinectin
-
-
recombinant human MPO
-
-
rhMPO
-
-
tissue myeloperoxidase
-
-
ORGANISM
COMMENTARY
LITERATURE
SEQUENCE CODE
SEQUENCE DB
SOURCE
Armoracia sp.
-
-
-
Manually annotated by BRENDA team
horse, myeloperoxidase
-
-
Manually annotated by BRENDA team
myeloperoxidase
-
-
Manually annotated by BRENDA team
myeloperoxidase and eosinophil peroxidase
-
-
Manually annotated by BRENDA team
myeloperoxidase has six isozymes
-
-
Manually annotated by BRENDA team
japanese radish, 18 isozymes, here JRPa and JRPc
-
-
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
malfunction
-
mice deficient in myeloperoxidase are more likely than wild type mice to die from infection by polymicrobial sepsis
physiological function
-
oxidation of serotonin by myeloperoxidase may profoundly influence inflammatory processes
physiological function
-
myeloperoxidase plays a fundamental role in oxidant production by neutrophils
physiological function
-
balance between peroxidase and chlorinating activities of myeloperoxidase is very important for the enhancement of antimicrobial action and prevention of damage caused by hypochlorite
physiological function
-
upon the action of the MPO-H2O2-chloride system, two of the major functional activities of kininogens: the susceptibility of high-molecular mass kininogen and low-molecular mass kininogen to kinin-forming action of kallikreins and the prekallikrein-binding capability of high-molecular mass kininogen, are dramatically impaired
physiological function
-
MPO is involved in the defence mechanism of the body against microorganisms
physiological function
-
hypochlorite formed by the MPO-H2O2-Cl- system is responsible for modification in unsaturated phosphatidylcholines (e.g. 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2arachidonoyl-sn-glycero-3-phosphocholine, 1-stearoyl-2-linoleoyl-sn-glycero-3-phosphocholine, or 1-palmitoyl-2-docosahexenoyl-sn-glycero-3-phosphocholine). The formation of lysophospholipids and chlorohydrins from unsaturated phosphatidylcholines by myeloperoxidase can be relevant in vivo under acute inflammatory conditions
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
physiological function
-
human neutrophils use the myeloperoxidase-hydrogen peroxide-chloride system to chlorinate but not nitrate Escherichia coli proteins during phagocytosis
physiological function
-
HOCl generated by the MPO-H2O2-chloride system inactivates tissue inhibitor of metalloproteinase-1 by oxidizing its N-terminal cysteine
physiological function
-
myeloperoxidase protects against sepsis in vivo by producing halogenating species, myeloperoxidase plays an important role in host defense against bacterial pathogens
physiological function
-
enzyme binds to the extracellular matrix proteins collagen IV and fibronectin, and this association is enhanced by the pre-incubation of these proteins with glycosaminoglycans. Correspondingly, an excess of glycosaminoglycans in solution during incubation inhibits the binding of enzyme to collagen IV and fibronectin. The oxidizing and chlorinating potential of myeloperoxidase is preserved upon binding to collagen IV and fibronectin, even the potentiation of enzyme activity in the presence of collagen IV and fibronectin is observed
SUBSTRATE
PRODUCT                      
REACTION DIAGRAM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
(-)-epicatechin + H2O2
? + H2O
show the reaction diagram
-
-
-
-
?
1-acetyl-4-(methylsulfanyl)benzene + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
1-chloro-4-(methylsulfanyl)benzene + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
1-methoxy-4-(methylsulfanyl)benzene + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
1-methyl-4-(methylsulfanyl)benzene + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
1-nitro-4-(methylsulfanyl)benzene + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine + Br- + H2O2
?
show the reaction diagram
-
the formation of bromohydrins by the MPO-H2O2-bromide system using physiological chloride concentrations occurs only at acidic pH values but not at pH 7.4
-
-
?
1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine + Cl- + H2O2
?
show the reaction diagram
-
the formation of chlorohydrins by the MPO-H2O2-chloride system using physiological chloride concentrations occurs only at acidic pH values but not at pH 7.4
-
-
?
2,2'-azino-bis-(3-ethylbenzthiazole-6-sulfonic acid) + H2O2
? + H2O
show the reaction diagram
-
both properoxinectin and peroxinectin are catalytically active as peroxidases
-
-
?
2-phenylenediamine + H2O2
?
show the reaction diagram
-
-
-
-
?
3,4-dihydroxyphenylacetic acid + H2O2
? + H2O
show the reaction diagram
-
-
-
-
?
4-(methylsulfanyl)aniline + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
4-tolyl methyl sulfide + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
5-cyanoindole + H2O2
?
show the reaction diagram
-
-
-
-
?
5-hydroxytryptamine + H2O2
?
show the reaction diagram
-
-
-
-
?
5-nitroindole + H2O2
?
show the reaction diagram
-
-
-
-
?
ascorbate + H2O2
?
show the reaction diagram
-
-
-
-
?
benzothiophene + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
benzyl methyl sulfide + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
Br- + H2O2
?
show the reaction diagram
P05164
-
-
-
?
Br- + H2O2
?
show the reaction diagram
-
-
-
-
?
Br- + H2O2
HBrO + H2O
show the reaction diagram
-
at physiological concentrations of chloride and bromide, hypobromous acid can be a major oxidant produced by myeloperoxidase
-
-
?
Br- + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
Br- + H2O2 + H+
HBrO + H2O
show the reaction diagram
-
-
-
-
?
catechol + H2O2
? + H2O
show the reaction diagram
-
-
-
-
?
chloride + H2O2
hypochlorous acid + H2O
show the reaction diagram
-
-
-
-
?
Cl- + H2O2
HOCl + H2O
show the reaction diagram
-
-
-
?
Cl- + H2O2
?
show the reaction diagram
P05164
-
-
-
?
Cl- + H2O2
HClO + H2O
show the reaction diagram
-
-
-
-
?
Cl- + H2O2
HClO + H2O
show the reaction diagram
-
main reducing substrate for myeloperoxidase
-
-
?
Cl- + H2O2 + chloroacetonitrile
HClO + H2O + cyanide
show the reaction diagram
-
chloride ion (Cl-) is the dominant electron donor, chloroacetonitrile is activated to cyanide by myeloperoxidase/H2O2/Cl- system in vitro
-
-
?
Cl- + H2O2 + H+
HClO + H2O
show the reaction diagram
-
-
-
-
?
Cl- + H2O2 + H+
HClO + H2O
show the reaction diagram
-
-
-
-
?
Cl- + H2O2 + H+
HClO + H2O
show the reaction diagram
-
-
-
-
?
Cl- + H2O2 + H+
HClO + H2O
show the reaction diagram
-
physiological substrate of myeloperoxidase
-
-
?
Cl- + H2O2 + H+
HClO + H2O
show the reaction diagram
-
at acidic pH, chlorinating activity of MPO dominates
-
-
?
Cl- + H2O2 + H+ + taurine + H+
taurine monochloroamine + 2 H2O
show the reaction diagram
-
the taurine chlorination reaction mediated by the myeloperoxidase system in vivo may involve an enzyme intermediate species rather than free HOCl
-
-
?
donor + H2O2
oxidized donor + H2O
show the reaction diagram
-
-, involved in immune defense reactions
-
-
r
donor + HOCl
oxidized donor + Cl-
show the reaction diagram
-
-, involved in immune defense reactions
-
-
r
dopamine + H2O2
? + H2O
show the reaction diagram
-
-
-
-
?
guaiacol + H2O2
tetraguaiacol + H2O
show the reaction diagram
-
-
-
-
?
guaiacol + H2O2
tetraguaiacol + H2O
show the reaction diagram
-
-
-
-
?
guaiacol + H2O2
?
show the reaction diagram
-
at neutral pH MPO has higher affinity to peroxidase substrate guaiacol
-
-
?
I- + H2O2
?
show the reaction diagram
-
-
-
-
?
I- + H2O2
?
show the reaction diagram
P05164
-
-
-
?
I- + H2O2
?
show the reaction diagram
Bos taurus, Armoracia sp.
-
-
-
-
?
I- + H2O2
?
show the reaction diagram
-
myeloperoxidase plays a fundamental role in oxidant production by neutrophils
-
-
?
I- + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
I- + H2O2 + H+
HIO + H2O
show the reaction diagram
-
-
-
-
?
I- + H2O2 + H+
HIO + H2O
show the reaction diagram
-
iodide is a better electron donor for MPO compound I than Br-
-
-
?
indole + H2O2
?
show the reaction diagram
-
-
-
-
?
low-density lipoprotein + Cl- + H2O2
? + H2O
show the reaction diagram
-
-
enzyme produces oxidative modifications of the protein moiety of low density lipoproteins
-
?
monochlorodimedon + Cl-
dichlorodimedon
show the reaction diagram
-
-
-
-
?
monochlorodimedone + H2O2
?
show the reaction diagram
-
-
-
-
?
myricitrin + H2O2
? + H2O
show the reaction diagram
-
myeloperoxidase is less efficient at oxidizing myricitrin at higher concentrations (0.05 mM) of H2O2
-
-
?
NADH + O2 + H+
NAD+ + H2O2
show the reaction diagram
-
myeloperoxidase is capable of catalyzing an oscillating peroxidase-oxidase reaction, when chloride is present in the reaction mixture
-
-
?
nitric oxide + H2O2
?
show the reaction diagram
-
-
-
-
?
nitrite + H2O2
?
show the reaction diagram
-
-
-
-
?
nitrite + L-tyrosine + H2O2 + H+
?
show the reaction diagram
-
poor substrate for myeloperoxidase, but free tyrosine facilitates nitration of tyrosyl residues by acting as a cosubstrate in the reaction
-
-
?
NO2- + H2O2
?
show the reaction diagram
-
-
-
-
?
o-dianisidine + H2O2
?
show the reaction diagram
-
-
-
-
?
o-dianisidine + H2O2
?
show the reaction diagram
-
-
-
-
?
o-dianisidine + H2O2
oxidized o-dianisidine + H2O
show the reaction diagram
-
-
-
-
?
phenyl propan-2-yl sulfide + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
quercetin + H2O2
oxidized quercetin + H2O
show the reaction diagram
-
-
-
-
?
SCN- + H2O2
OSCN- + H2O
show the reaction diagram
-
-
-
-
?
SCN- + H2O2
?
show the reaction diagram
P05164
-
-
-
?
serotonin + H2O2
serotonin dimer + H2O
show the reaction diagram
-
favoured substrate of myeloperoxidase, only ascorbate blocks oxidation of serotonin
-
-
?
serotonin + superoxide
tryptamine-4,5-dione + H2O
show the reaction diagram
-
-
-
-
?
taurine + Cl- + H2O2
taurine chloramine + ?
show the reaction diagram
-
-
-
-
?
taurine + Cl- + H2O2
taurine chlormaine + HeO
show the reaction diagram
-
-
-
-
?
tetramethylbenzidine + H2O2
?
show the reaction diagram
-
-
-
-
?
tetramethylbenzidine + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
thioanisole + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
thiocyanate + H2O2
hypothiocyanite + H2O
show the reaction diagram
-
-
-
-
?
thiocyanate + H2O2 + H+
hypothiocyanite + H2O
show the reaction diagram
-
thiocyanate is a major physiological substrate of myeloperoxidase and most favoured substrate compared to chloride and bromide, thiocyanate is the most favoured substrate compared to chloride and bromide. With 0.1 mM thiocyanate about 50% of the H2O2 present is converted into hypothiocyanite, the rate of H2O2 loss catalysed by myeloperoxidase in the presence of 100 mM chloride doubles when 0.1 mM thiocyanate is added, and is maximal with 1 mM thiocyanate
-
-
?
thiocyanate + H2O2 + H+
?
show the reaction diagram
-
-
-
-
?
thiocyanate + H2O2 + H+
hypothiocyanate + H2O
show the reaction diagram
-
-
-
-
?
tryptamine + H2O2
?
show the reaction diagram
-
-
-
-
?
tyrosine + H2O2
?
show the reaction diagram
-
-
-
-
?
tyrosine + H2O2
dityrosine + H2O
show the reaction diagram
-
-
-
-
?
urate + H2O2
5-hydroxyisourate + H2O
show the reaction diagram
-
-
-
-
?
monochlorodimedone + H2O2
dichlorodimedone + H2O
show the reaction diagram
-
-
-
-
?
additional information
?
-
-
analysis of kinetics for eosinophil peroxidase and myeloperoxidase
-
-
-
additional information
?
-
-
antimicrobial function
-
-
-
additional information
?
-
-
myeloperoxidase kills microorganisms via a reaction that involves H2O2 and a halide
-
-
-
additional information
?
-
-
possible role of the enzyme for neutrophil myeloperoxidase in cystic fibrosis lung disease
-
-
-
additional information
?
-
P05164
halides serve as substrates or inhibitors, existence of two halide binding sites that have a distinct impact on the heme iron microenvironment in myeloperoxidase
-
-
-
additional information
?
-
-
myeloperoxidase mediates protein tyrosine nitration
-
-
-
additional information
?
-
-
bromide, at physiological concentrations, promotes a dramatic increase in bromination of human serum albumin catalyzed by myeloperoxidase
-
-
-
additional information
?
-
-
HClO released from the enzyme chlorinates L-Pro-Gly-Gly producing N-chloro-L-Pro-Gly-Gly. L-taurine, a smaller substrate, may be chlorinated in the heme product of the enzyme
-
-
-
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
-
-
-
additional information
?
-
-
in the presence of the complete MPO/H2O2/Cl- system, lyso-products and chlorohydrins are only formed at pH values lower than pH 6.0 with an optimum at pH 4.3
-
-
-
additional information
?
-
-
myeloperoxidase generates 3-chlorotyrosine and 3-bromotyrosine during sepsis. In the brominating pathway, myeloperoxidase initially produces HOCl, which reacts with Br2 to generate brominating intermediates. Both chlorination and bromination of N-acetyl-L-tyrosine to N-acetyl-L-3-chlorotyrosine or N-acetyl-L-3-bromotyrosine are optimal under acidic conditions, but significant levels of the halogenated amino acids are also generated at neutral pH. Under acidic (pH 5.9) and neutral conditions, bromination by myeloperoxidase requires both enzyme and H2O2, it is inhibited by catalase (a peroxide scavenger), sodium azide (a heme poison), and taurine (a scavenger of hypohalous acids)
-
-
-
additional information
?
-
-
only amino acids with free amino and carboxylic acid groups on the alpha-carbon yield aldehydes when oxidized by the myeloperoxidase-H2O2-Cl- system. Incubation of the alpha-amino blocked analog Nalpha-acetyllysine with the complete myeloperoxidase system fails to generate detectable aldehyde
-
-
-
NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
ascorbate + H2O2
?
show the reaction diagram
-
-
-
-
?
Br- + H2O2
?
show the reaction diagram
-
-
-
-
?
Cl- + H2O2
HClO + H2O
show the reaction diagram
-
-
-
-
?
Cl- + H2O2
HClO + H2O
show the reaction diagram
-
main reducing substrate for myeloperoxidase
-
-
?
Cl- + H2O2 + H+
HClO + H2O
show the reaction diagram
-
-
-
-
?
Cl- + H2O2 + H+
HClO + H2O
show the reaction diagram
-
physiological substrate of myeloperoxidase
-
-
?
Cl- + H2O2 + H+ + taurine + H+
taurine monochloroamine + 2 H2O
show the reaction diagram
-
the taurine chlorination reaction mediated by the myeloperoxidase system in vivo may involve an enzyme intermediate species rather than free HOCl
-
-
?
donor + H2O2
oxidized donor + H2O
show the reaction diagram
-
involved in immune defense reactions
-
-
r
donor + HOCl
oxidized donor + Cl-
show the reaction diagram
-
involved in immune defense reactions
-
-
r
I- + H2O2
?
show the reaction diagram
-
-
-
-
?
I- + H2O2
?
show the reaction diagram
-
myeloperoxidase plays a fundamental role in oxidant production by neutrophils
-
-
?
nitric oxide + H2O2
?
show the reaction diagram
-
-
-
-
?
nitrite + H2O2
?
show the reaction diagram
-
-
-
-
?
thiocyanate + H2O2
hypothiocyanite + H2O
show the reaction diagram
-
-
-
-
?
thiocyanate + H2O2 + H+
hypothiocyanite + H2O
show the reaction diagram
-
thiocyanate is a major physiological substrate of myeloperoxidase and most favoured substrate compared to chloride and bromide
-
-
?
tyrosine + H2O2
?
show the reaction diagram
-
-
-
-
?
urate + H2O2
5-hydroxyisourate + H2O
show the reaction diagram
-
-
-
-
?
monochlorodimedon + Cl-
dichlorodimedon
show the reaction diagram
-
-
-
-
?
additional information
?
-
-
antimicrobial function
-
-
-
additional information
?
-
-
myeloperoxidase kills microorganisms via a reaction that involves H2O2 and a halide
-
-
-
additional information
?
-
-
possible role of the enzyme for neutrophil myeloperoxidase in cystic fibrosis lung disease
-
-
-
COFACTOR
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
heme
-
myeloperoxidase
heme
Armoracia sp.
-
the free carboxyl groups at position 6 and 7 of the porphyrin ring are essential for catalytic activity
heme
-
derivative of mesoporphyrin IX
heme
-
heme containing enzyme
METALS and IONS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
Ca2+
-
-
Fe
Armoracia sp., Bos taurus
-
-
Fe
-
two atoms of iron per molecule, high-spin
INHIBITORS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
3-methoxybenzoic acid hydrazide
-
-
-
3-nitrobenzoic acid hydrazide
-
-
-
4'-amino-4-fluorochalcone
-
potent inhibition of the chlorinating activity. Compound is not toxic to neutrophils at concentrations below 100 microM
-
4'-amino-4-methylchalcone
-
potent inhibition of the chlorinating activity. Compound is not toxic to neutrophils at concentrations below 100 microM
-
4'-aminochalcone
-
potent inhibition of the chlorinating activity. Compound is not toxic to neutrophils at concentrations below 100 microM
-
4-(5-fluoro-1H-indol-3-yl)butanamide
-
reversible myeloperoxidase inhibitor, efficiently prevents enzyme-dependent LDL oxidation
4-(7-fluoro-1H-indol-3-yl)butanamide
-
-
4-aminobenzoic acid hydrazide
-
most potent inhibitor of peroxidation, it irreversibly inhibits HOCl production by the purified myeloperoxidase. With neutrophils stimulated with opsonized zymosan or phorbol myristate acetate, 4-aminobenzoic acid hydrazide inhibits HOCI production by up to 90%
4-aminobenzoic acid hydrazine
-
metabolism of chloroacetonitrile to cyanide by MPO/H2O2/Cl- system is significantly reduced by 4-amino benzoic acid hydrazine to 52.6% of control value
-
4-chlorobenzoic acid hydrazide
-
-
-
4-hydroxy-2,2,6,6-tetra-methyl-1-piperidinyloxy radical
-
tempol, 0.01 mM tempol efficiently inhibits peroxidase-mediated RNase nitration
4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl
-
i.e. tempol, inhibits both H2O2 consumption and taurine chlorination, reacts mostly as a reversible inhibitor of MPO by trapping it as MPO-II and the MPO-II-tempol complex, which are not within the chlorinating cycle
-
4-hydroxybenzoic acid hydrazide
-
-
-
4-methoxybenzoic acid hydrazide
-
-
-
5-(7-fluoro-1H-indol-3-yl)pentanamide
-
-
5-chlorotryptamine
-
IC50: 0.00073 mM
5-fluorotryptamine
-
IC50: 0.00079 mM
5-thio-2-nitrobenzoic acid
-
competitive inhibitor of myeloperoxidase
Aminotriazole
-
3 mM inhibitory
benzoic hydrazide
-
-
betanin
-
higher micromolar betanin concentrations inhibit the MPO-mediated chlorination reactions by scavenging of hypochlorous acid
-
Br-
-
bromide binding to the halide-binding site responsible for shifts in the Soret band of the absorption spectrum of myeloperoxidase inhibits the enzyme by effectively competing with H2O2 for access to the distal histidine
catalase
-
addition of the antioxidant enzyme catalase to incubation mixtures results in 56.1% decrease in cyanide release by MPO/H2O2/Cl- system
-
dityrosine
-
inhibits MPO-derived dityrosine formation in a dose-dependent manner
H2O2
-
higher concentrations than 0.135 mM inhibitory
H2O2
-
at pH 5.0, H2O2 at high concentrations inhibits the enzyme. The rate of sulfoxide formation increases as the H2O2 concentration increases up to 0.2 mM, while a further increase in concentration results in a decrease in the rate of sulfoxide formation (40% inhibition at 1 mM H2O2)
H2O2
-
inhibition of taurine chlorination by H2O2 becomes significant at about pH 6.6 and higher
indicaxanthin
-
at neutral pH and depending on their concentration, indicaxanthin can exhibit a stimulating and inhibitory effect on the chlorination activity of MPO, whereas at pH 5.0 only inhibitory effects are observed even at micromolar concentrations
-
Indomethacin
-
metabolism of chloroacetonitrile to cyanide by MPO/H2O2/Cl- system is significantly reduced by indomethacin to 88.9% of control value
kaempferol
-
35% inhibition at 0.1 mM for 10 min
kaempferol
-
-
kaempferol-7-O-rhamnoside
-
8% inhibition at 0.1 mM for 10 min
myricetin
-
75% inhibition at 0.1 mM for 10 min
myricetin
-
-
Myricitrin
-
51% inhibition at 0.1 mM for 10 min
NaN3
-
0.3 mM inhibitory
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
o-Dianisidine
-
higher concentrations than 1.54 mM inhibitory
Q3GA
-
inhibits MPO-derived dityrosine formation in a dose-dependent manner
quercetin
-
42% inhibition at 0.1 mM for 10 min
quercetin
-
potent inhibitor, inhibits MPO-derived dityrosine formation in a dose-dependent manner
Salicylhydroxamic acid
-
salicylhydroxamic acid is a much poorer inhibitor of HOCI production with neutrophils stimulated with opsonized zymosan (0.2 mM is required for complete inhibition)
serotonin
-
at higher concentrations than 0.02 mM, serotonin almost completely blocks the formation of hypochlorite
Sodium azide
-
-
Sodium azide
-
metabolism of chloroacetonitrile to cyanide by MPO/H2O2/Cl- system is significantly reduced by sodium azide to 43.9% of control value
Sulfide
-
at high sulfide concentrations, enzymic inhibition is observed above 0.25 mM (20% inhibition at 0.3 mM sulfide)
-
taxifolin
-
-
additional information
-
halides serve as substrates or inhibitors, existence of two halide binding sites that have a distinct impact on the heme iron microenvironment in myeloperoxidase
-
ACTIVATING COMPOUND
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
5-aminosalicylic acid
-
converts inactive myeloperoxidase compound II rapidly into active myeloperoxidase
ascorbic acid
-
200% activation at 0.002 mM and pH 5.2
ascorbic acid
-
converts inactive myeloperoxidase compound II into active myeloperoxidase
betanin
-
low micromolar betanin concentrations enhance the chlorination activity of MPO at pH 7.0, increasing the betanin concentration up to 0.006 mM dramatically increases the chlorination rate of monochlorodimedon
-
chloride
-
in the presence of 100 mM NaCl the catalytic efficiency of MPO increases 3-4fold whatever the sulfide considered, the rate of 4-tolyl methyl sulphide oxidation enhancement is about 8fold at 120 mM NaCl
D-penicillamine
-
addition of D-penicillamine significantly enhances the rate of chloroacetonitrile oxidation and cyanide release by the myeloperoxidase/H2O2/Cl- system (17.2% increase at 5 mM)
ferrocyanide
-
converts inactive myeloperoxidase compound II into active myeloperoxidase
glutathione
-
addition of glutathione significantly enhances the rate of chloroacetonitrile oxidation and cyanide release by the myeloperoxidase/H2O2/Cl- system (24% increase at 5 mM)
indicaxanthin
-
at neutral pH and depending on their concentration, indicaxanthin can exhibit a stimulating and inhibitory effect on the chlorination activity of MPO
-
myelin oligodendrocyte protein
-
MPO activity increases significantly in the myelin oligodendrocyte protein treated rats (0.05 mg)
-
N-acetyl-L-cysteine
-
addition of N-acetyl-L-cysteine significantly enhances the rate of chloroacetonitrile oxidation and cyanide release by the myeloperoxidase/H2O2/Cl- system (16.3% increase at 5 mM)
NaCl
-
maximal activity in the presence of 200 mM NaCl
serotonin
-
at low micromolar concentrations (below 0.02 mM), serotonin enhances hypochlorite production by both purified myeloperoxidase and neutrophils
L-cysteine
-
addition of L-cysteine significantly enhances the rate of chloroacetonitrile oxidation and cyanide release by the myeloperoxidase/H2O2/Cl- system (45.4% increase at 5 mM)
additional information
-
hypercholesterolemia results in higher tissue MPO activities, the influences of fish oil on MPO activities are not obvious in hypercholesterolemic mice with sepsis
-
KM VALUE [mM]
KM VALUE [mM] Maximum
SUBSTRATE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
0.016
-
1-acetyl-4-(methylsulfanyl)benzene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
0.039
-
1-acetyl-4-(methylsulfanyl)benzene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
0.027
-
1-chloro-4-(methylsulfanyl)benzene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.067
-
1-chloro-4-(methylsulfanyl)benzene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.012
-
1-methoxy-4-(methylsulfanyl)benzene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.03
-
1-methoxy-4-(methylsulfanyl)benzene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.032
-
1-methyl-4-(methylsulfanyl)benzene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.04
-
1-methyl-4-(methylsulfanyl)benzene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.066
-
1-nitro-4-(methylsulfanyl)benzene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
0.076
-
1-nitro-4-(methylsulfanyl)benzene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
0.52
-
3,4-dihydroxyphenylacetic acid
-
25C, pH 5.5
21.9
-
3,4-dihydroxyphenylacetic acid
-
25C, pH 5.5
0.057
-
4-(methylsulfanyl)aniline
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
0.104
-
4-(methylsulfanyl)aniline
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
0.072
-
benzothiophene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.081
-
benzothiophene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.05
-
benzyl methyl sulfide
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.083
-
benzyl methyl sulfide
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
2
-
Br-
-
in 100 mM phosphate buffer, pH 7.4, at 21C
1.84
-
catechol
-
25C, pH 5.5
21.1
-
catechol
-
25C, pH 5.5
0.089
-
Chloroacetonitrile
-
at pH 5.5, 37C, 0.1 mM KCl, 0.5 mM H2O2, 0.15 mM chloroacetonitrile, 5 units/ml MPO, and 0.25 mM NaOCl during an incubation period of 60 min
175
-
Cl-
-
in 100 mM phosphate buffer, pH 7.4, at 21C
0.64
-
dopamine
-
25C, pH 5.5
136.3
-
dopamine
-
25C, pH 5.5
0.03
-
H2O2
-
apparent value, measured after 100 ms, in 50 mM phosphate buffer, at pH 7.2 and 20C
0.07
-
H2O2
-
in 50 mM acetate buffer, pH 5.0, at 20C
0.026
-
phenyl propan-2-yl sulfide
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
0.041
-
phenyl propan-2-yl sulfide
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
0.25
-
SCN-
-
25C, pH 5.5
0.29
-
SCN-
-
25C, pH 5.5
0.018
-
thioanisole
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.02
-
thioanisole
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.5
-
Thiocyanate
-
in 100 mM phosphate buffer, pH 7.4, at 21C
TURNOVER NUMBER [1/s]
TURNOVER NUMBER MAXIMUM[1/s]
SUBSTRATE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
4.2
-
1-acetyl-4-(methylsulfanyl)benzene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
56
-
1-acetyl-4-(methylsulfanyl)benzene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
5
-
1-chloro-4-(methylsulfanyl)benzene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
35
-
1-chloro-4-(methylsulfanyl)benzene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
0.43
-
1-methoxy-4-(methylsulfanyl)benzene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
6
-
1-methoxy-4-(methylsulfanyl)benzene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
3
-
1-methyl-4-(methylsulfanyl)benzene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
20
-
1-methyl-4-(methylsulfanyl)benzene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
1.8
-
1-nitro-4-(methylsulfanyl)benzene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
5.5
-
1-nitro-4-(methylsulfanyl)benzene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
10
-
4-(methylsulfanyl)aniline
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
40
-
4-(methylsulfanyl)aniline
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
1
-
benzothiophene
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
1.6
-
benzothiophene
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
1
-
benzyl methyl sulfide
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
8
-
benzyl methyl sulfide
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
1.2e-05
-
catechol
-
25C, pH 5.5
2.2e-05
-
catechol
-
25C, pH 5.5
28.5
-
Cl-
-
at 21C in 50 mM sodium phosphate buffer, pH 7.4
1e-07
-
dopamine
-
25C, pH 5.5
1.6e-06
-
dopamine
-
25C, pH 5.5
13
-
H2O2
-
apparent value, measured after 15 s, in 50 mM phosphate buffer, at pH 7.2 and 20C
25
-
H2O2
-
apparent value, measured after 1 s, in 50 mM phosphate buffer, at pH 7.2 and 20C
320
-
H2O2
-
apparent value, measured after 100 ms, in 50 mM phosphate buffer, at pH 7.2 and 20C
0.7
-
nitrite
-
at 21C in 50 mM sodium phosphate buffer, pH 7.4
7.3
-
phenyl propan-2-yl sulfide
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
14
-
phenyl propan-2-yl sulfide
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
-
1.6e-07
-
SCN-
-
25C, pH 5.5
3.3e-06
-
SCN-
-
25C, pH 5.5
4
-
thioanisole
-
in the absence of NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
12
-
thioanisole
-
in the presence of 100 mM NaCl, in 50 mM acetate buffer, pH 5.0, at 20C
30.5
-
Thiocyanate
-
at 21C in 50 mM sodium phosphate buffer, pH 7.4
IC50 VALUE [mM]
IC50 VALUE [mM] Maximum
INHIBITOR
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
0.00025
-
4'-amino-4-fluorochalcone, 4'-amino-4-methylchalcone
-
pH not specified in the publication, temperature not specified in the publication
-
0.000265
-
4'-aminochalcone
-
pH not specified in the publication, temperature not specified in the publication
-
1.8e-05
-
4-(5-fluoro-1H-indol-3-yl)butanamide
-
low density lipoprotein oxidation, pH 7.2, 37C; taurine chlorination, pH 7.2, 37C
2.4e-05
-
4-(7-fluoro-1H-indol-3-yl)butanamide
-
low density lipoprotein oxidation, pH 7.2, 37C
2.6e-05
-
4-(7-fluoro-1H-indol-3-yl)butanamide
-
taurine chlorination, pH 7.2, 37C
0.0003
-
4-aminobenzoic acid hydrazide
-
at 37C, in 50 mM acetate buffer, pH 5.4
3.4e-05
-
5-(7-fluoro-1H-indol-3-yl)pentanamide
-
taurine chlorination, pH 7.2, 37C
4.4e-05
-
5-(7-fluoro-1H-indol-3-yl)pentanamide
-
low density lipoprotein oxidation, pH 7.2, 37C
0.00073
-
5-chlorotryptamine
-
IC50: 0.00073 mM
0.00079
-
5-fluorotryptamine
-
IC50: 0.00079 mM
0.00387
-
fisetin
-
-
0.032
-
HClO
-
hemi-MPO, in in 150 mM KCI and 50 mM potassium phosphate pH 7.2, at 20C
0.05
-
HClO
-
dimeric MPO, in in 150 mM KCI and 50 mM potassium phosphate pH 7.2, at 20C
0.00208
-
kaempferol
-
-
0.00422
-
luteolin
-
-
0.0013
-
nitrite
-
at 21C in 50 mM sodium phosphate buffer, pH 7.4
0.00127
-
quercetin
-
-
0.032
-
Salicylhydroxamic acid
-
at 37C, in 50 mM acetate buffer, pH 5.4
0.00663
-
taxifolin
-
-
0.0093
-
Urate
-
pH and temperature not specified in the publication
SPECIFIC ACTIVITY [µmol/min/mg]
SPECIFIC ACTIVITY MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
additional information
-
-
7.9 units/mg (spent culture medium, using 2-phenylenediamine as substrate, in 100 mM sodium phosphate, pH 5.0, 150 mM NaCl, at 25C), 537 units/mg (recombinant enzyme after 67.8fold purification, using 2-phenylenediamine as substrate, in 100 mM sodium phosphate, pH 5.0, 150 mM NaCl, at 25C), 857 units/mg (recombinant enzyme after 67.8fold purification, using O-dianisidine as substrate, in 100 mM sodium phosphate, pH 5.0, 150 mM NaCl, at 25C), 800 units/mg (natural MPO, using O-dianisidine as substrate, in 100 mM sodium phosphate, pH 5.0, 150 mM NaCl, at 25C)
pH OPTIMUM
pH MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
4.5
5
-
with o-dianisidine
4.5
5
-
a maximum of MPO-mediated chlorination rate is observed for L-Pro-Gly-Gly and Tau when [H2O2] is 0.3-0.7 mM and pH is at 4.5-5.0
4.7
6
-
optimum pH for peroxidase activity of MPO
5
-
-
maximal activity around pH 5.0, recombinant and natural MPO
5.2
-
-
-
5.5
-
-
myeloperoxidase
5.5
-
-
with iodide
5.5
-
-
optimum pH for the activation of chloroacetonitrile to cyanide by the myeloperoxidase/H2O2/Cl- system
5.8
-
-
with 0.002 mM ascorbic acid as activator
7.4
-
-
optimum pH for chlorinating activity of MPO, at pH 7.4 chloride ions do not compete with guaiacol up to the concentration of 150 mM
pH RANGE
pH RANGE MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
5
7.8
-
between pH 5.0 and 7.0, myeloperoxidase converts about 90% of available hydrogen peroxide to hypochlorous acid and the remainder to hypobromous acid. Above pH 7, there is an abrupt rise in the yield of hypobromous acid. At pH 7.8, it accounts for 40% of the hydrogen peroxide
TEMPERATURE OPTIMUM
TEMPERATURE OPTIMUM MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
37
-
-
optimum temperature for the activation of chloroacetonitrile to cyanide by the myeloperoxidase/H2O2/Cl- system
SOURCE TISSUE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
SOURCE
-
atherosclerotic aorta
Manually annotated by BRENDA team
-
in homogenates of multiple sclerosis white matter, demyelination is associated with significantly elevated MPO activity
Manually annotated by BRENDA team
-
polymorphonuclear
Manually annotated by BRENDA team
-
neutrophilic granulocytes
Manually annotated by BRENDA team
Armoracia sp.
-
-
Manually annotated by BRENDA team
-
of cystic fibrosis
Manually annotated by BRENDA team
LOCALIZATION
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
-
cytoplasmic granule
Manually annotated by BRENDA team
MOLECULAR WEIGHT
MOLECULAR WEIGHT MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
15500
-
-
SDS-PAGE under reducing conditions gives three bands with molecular masses of 57000, 39000 and 15000 Da, respectively
39000
-
-
SDS-PAGE under reducing conditions gives three bands with molecular masses of 57000, 39000 and 15000 Da, respectively
41500
-
-
JRPc, SDS-PAGE
54500
-
-
JRPa, SDS-PAGE
57000
-
-
SDS-PAGE under reducing conditions gives three bands with molecular masses of 57000, 39000 and 15000 Da, respectively
110000
-
-
dimeric mature enzyme, SDS-PAGE
150000
-
-
native PAGE
150000
-
-
natural MPO, gel filtration
SUBUNITS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
dimer
-
disufide-linked dimer, myeloperoxidase
dimer
-
1 * 57000 + 1 * 10500, myeloperoxidase, SDS-PAGE
dimer
-
-
homodimer
-
2 * 84000, recombinant MPO is secreted essentially as a monomeric, heme-containing, single-chain precursor of 84000 Da which exhibits peroxidase activity, gel filtration
homodimer
-
2 * 84000, human recombinant unprocessed myeloperoxidase, SDS-PAGE
homodimer
-
x-ray crystallography
monomer
-
1 * 70000, eosinophil peroxidase
tetramer
-
two heavy and two light subunits, SDS-PAGE
POSTTRANSLATIONAL MODIFICATION
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
glycoprotein
Armoracia sp.
-
16.8-21% carbohydrate content
glycoprotein
-
10% carbohydrate by weight
glycoprotein
-
-
glycoprotein
-
small subunit less glycosylated than big one
glycoprotein
-
recombinant MPO has a high mannose content of 7.7%, clearly higher than the level found in the natural enzyme (4.6%)
glycoprotein
-
-
proteolytic modification
-
extracellular processing of properoxinectin into an active cell adhesion protein
glycoprotein
-
28% carbohydrate by weight
Crystallization/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
hanging drop vapor diffusion method, native MPO is crystallized with 16% (w/v) polyethylene glycol (PEG) 8000, 50 mM ammonium sulfate, 50 mM sodium acetate, 2 mM calcium acetate, and 50 mM sodium thiocyanate at 22C and pH 5.5 for 24 h
-
hanging drop vapor diffusion method, using 50 mM sodium acetate (pH 5.5), 50 mM ammonium sulfate, 2 mM calcium chloride, and 22-25% (w/v) PEG 8k, at 18C
-
pH STABILITY
pH STABILITY MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
7.2
-
-
the enzymic activity at pH 7.2 rapidly declines in time (from 100 ms up to 15 s)
TEMPERATURE STABILITY
TEMPERATURE STABILITY MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
65
-
-
5 min without inactivation
80
-
-
at 80C the native dimeric MPO retains remarkable stability (50% activity left after 72 min), but hemi-MPO has already been inactivated by 50% after 4.5 min
GENERAL STABILITY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
denaturation with 3.1 M guanidinium hydrochloride
-
STORAGE STABILITY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
-20C, 0.1 M sodium acetate, pH 5.6, 0.5 M CaCl2, 0.05% w/v cetyltrimethylammonium bromide, 25% glycerol, many months, no activity loss, can be thawed and refrozen
-
Purification/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
purified from raw milk
-
Q-Sepharose column chromatography, carboxymethyl-Sepharose column chromatography, chelating-Sepharose column chromatography, and Sephacryl S200 gel filtration
-
recombinant MPO
-
Cloned/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
expressed in CHO cell line 24.1.7
-
expression in CHO cells
-
human recombinant unprocessed monomeric myeloperoxidase is expressed in CHO cells
-
EXPRESSION
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
urate enhances MPO-dependent consumption of nitric oxide
-
APPLICATION
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
medicine
-
loading macrophages with exogenous myeloperoxidase could enhance their microbicidal activity, potentially useful therapeutic application
medicine
-
the enzyme is an interesting target for anti-inflammatory therapy
analysis
-
detection of myeloperoxidase activity in vivo by use of a paramagneitc substrate. The sensing probe is obtained by replacing the reducing substrate serotonin with 5-hydroxytryptophan. The resulting probe bis-hydroxytryptophan-gadolinium diethylenetriamine pentaacetic acid in vitro improves solubility in water, acts as a substrate, induces cross linking of proteins in the presence of myeloperoxidase,produces oxidation products which bind to plasma proteins and does not follow first order reaction kinetics. Bis-hydroxytryptophan-gadolinium diethylenetriamine pentaacetic acid is retained for up to five days in myeloperoxidase-containing sites and cleared faster than serotonin diethylenetriamine pentaacetic acid from enzyme-negative sites