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Literature summary for 1.6.5.10 extracted from

  • Endo, S.; Matsunaga, T.; Kitade, Y.; Ohno, S.; Tajima, K.; El-Kabbani, O.; Hara, A.
    Human carbonyl reductase 4 is a mitochondrial NADPH-dependent quinone reductase (2008), Biochem. Biophys. Res. Commun., 377, 1326-1330.
    View publication on PubMed

Cloned(Commentary)

Cloned (Comment) Organism
overexpression of CBR4 in bovine endothelial cells reveals that the enzyme has a non-cleavable mitochondrial targeting signal Homo sapiens

Inhibitors

Inhibitors Comment Organism Structure
Cibacron blue F3GA the 1,4-naphthoquinone activity of CBR4 is potently inhibited, competitive with respect to NADPH Homo sapiens
additional information the enzyme is insensitive to dicuomarol and quercetin, potent inhibitors of cytosolic quinone reductases Homo sapiens
NADP+ the 1,4-naphthoquinone activity of CBR4 is potently inhibited, competitive with respect to NADPH Homo sapiens
Procion red HE3B the 1,4-naphthoquinone activity of CBR4 is potently inhibited, competitive with respect to NADPH Homo sapiens

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.0016
-
9,10-phenanthrenequinone pH 7.4, 25°C Homo sapiens
0.0019
-
1,4-benzoquinone pH 7.4, 25°C Homo sapiens
0.003
-
1,2-naphthoquinone pH 7.4, 25°C Homo sapiens
0.003
-
2-methyl-1,4-naphthoquinone pH 7.4, 25°C Homo sapiens
0.0043
-
5-Hydroxy-2-methyl-1,4-naphthoquinone pH 7.4, 25°C Homo sapiens
0.0044
-
2,3-dimethoxy-5-methyl-1,4-benzoquinone pH 7.4, 25°C Homo sapiens
0.0045
-
5-hydroxy-1,4-naphthoquinone pH 7.4, 25°C Homo sapiens
0.0065
-
1,4-Naphthoquinone pH 7.4, 25°C Homo sapiens
0.036
-
menadione pH 7.4, 25°C Homo sapiens

Localization

Localization Comment Organism GeneOntology No. Textmining
mitochondrion CBR4 is a mitochondrial matrix protein, its N-terminal signal is not cleaved Homo sapiens 5739
-

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
25000
-
4 * 25000, SDS-PAGE Homo sapiens
100000
-
gel filtration Homo sapiens

Organism

Organism UniProt Comment Textmining
Homo sapiens
-
-
-

Source Tissue

Source Tissue Comment Organism Textmining
A-549 cell
-
Homo sapiens
-
Caco-2 cell
-
Homo sapiens
-
kidney
-
Homo sapiens
-
liver
-
Homo sapiens
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
1,2-naphthoquinone + NADPH + H+
-
Homo sapiens 1,2-naphthoquinol + NADP+
-
?
1,4-benzoquinone + NADPH + H+ 1,4-benzoquinone is oxidized almost stoichiometric amount of NADPH, suggesting that it is reduced to its hydroquinone with a two-electron reduction mechanism Homo sapiens 1,4-benzoquinol + NADP+
-
?
1,4-naphthoquinone + NADPH + H+ 1,4-naphthoquinone participates in the redox cycling in their reduction by this enzyme as evidenced by excess NADPH oxidation over quinone reduction. CBR4 may reduce 1,4-naphthoquinone in the two-electron reduction mechanism, but produces reactive superoxide and semiquinones through their redox cycling Homo sapiens 1,4-naphthoquinol + NADP+
-
?
2,3-dimethoxy-5-methyl-1,4-benzoquinone + NADPH + H+
-
Homo sapiens 2,3-dimethoxy-5-methyl-1,4-benzoquinol + NADP+
-
?
2-methyl-1,4-naphthoquinone + NADPH + H+
-
Homo sapiens 2-methyl-1,4-naphthoquinol + NADP+
-
?
5-hydroxy-1,4-naphthoquinone + NADPH + H+ 5-hydroxy-1,4-naphthoquinone participates in the redox cycling in their reduction by this enzyme as evidenced by excess NADPH oxidation over quinone reduction Homo sapiens 5-hydroxy-1,4-naphthoquinol + NADP+
-
?
5-hydroxy-2-methyl-1,4-naphthoquinone + NADPH + H+
-
Homo sapiens 5-hydroxy-2-methyl-1,4-naphthoquinol + NADP+
-
?
9,10-phenanthrenequinone + NADPH + H+ 9,10-phenanthrenequinone participates in the redox cycling in their reduction by this enzyme as evidenced by excess NADPH oxidation over quinone reduction. CBR4 may reduce 9,10-phenanthrenequinone in the two-electron reduction mechanism, but produces reactive superoxide and semiquinones through their redox cycling Homo sapiens 9,10-phenanthrenequinol + NADP+
-
?
menadione + NADPH + H+
-
Homo sapiens menadiol + NADP+
-
?
additional information the enzyme exhibits NADPH-dependent reductase activity for o- and p-quinones, but not for other aldehydes and ketones. In vitro quinone reduction by CBR4 generates superoxide through the redox cycling, and suggest that the enzyme may be involved in the induction of apoptosis by cytotoxic 9,10-phenanthrenequinone Homo sapiens ?
-
?

Subunits

Subunits Comment Organism
tetramer 4 * 25000, SDS-PAGE Homo sapiens

Synonyms

Synonyms Comment Organism
CBR4
-
Homo sapiens
NADPH-dependent quinone reductase
-
Homo sapiens

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
25
-
assay at Homo sapiens

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
0.068
-
2,3-dimethoxy-5-methyl-1,4-benzoquinone pH 7.4, 25°C Homo sapiens
0.19
-
5-hydroxy-1,4-naphthoquinone pH 7.4, 25°C Homo sapiens
0.195
-
1,4-Naphthoquinone pH 7.4, 25°C Homo sapiens
0.207
-
1,4-benzoquinone pH 7.4, 25°C Homo sapiens
0.21
-
1,2-naphthoquinone pH 7.4, 25°C Homo sapiens
0.212
-
menadione pH 7.4, 25°C Homo sapiens
0.305
-
9,10-phenanthrenequinone pH 7.4, 25°C Homo sapiens

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
6.5
-
-
Homo sapiens

Cofactor

Cofactor Comment Organism Structure
NADPH
-
Homo sapiens

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
0.0003
-
Procion red HE3B pH 7.4, 25°C Homo sapiens
0.001
-
Cibacron blue F3GA pH 7.4, 25°C Homo sapiens
0.057
-
NADP+ pH 7.4, 25°C Homo sapiens