Information on EC 1.6.2.2 - cytochrome-b5 reductase

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The expected taxonomic range for this enzyme is: Eukaryota

EC NUMBER
COMMENTARY hide
1.6.2.2
-
RECOMMENDED NAME
GeneOntology No.
cytochrome-b5 reductase
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
NADH + 2 ferricytochrome b5 = NAD+ + H+ + 2 ferrocytochrome b5
show the reaction diagram
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
oxidation
-
-
-
-
redox reaction
-
-
-
-
reduction
-
-
-
-
PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
Amino sugar and nucleotide sugar metabolism
-
-
SYSTEMATIC NAME
IUBMB Comments
NADH:ferricytochrome-b5 oxidoreductase
A flavoprotein (FAD).
CAS REGISTRY NUMBER
COMMENTARY hide
9032-25-1
-
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
gene CBR1
-
-
Manually annotated by BRENDA team
turnip
-
-
Manually annotated by BRENDA team
-
-
-
Manually annotated by BRENDA team
-
-
-
Manually annotated by BRENDA team
L. cv. Ogosta
-
-
Manually annotated by BRENDA team
Mucor racemosus PTCC 5305
strain PTCC 5305
SwissProt
Manually annotated by BRENDA team
learn-pyrethroid-resistance strain, house fly
-
-
Manually annotated by BRENDA team
akkaraman sheep
-
-
Manually annotated by BRENDA team
L. cv Dobrujanski 7
-
-
Manually annotated by BRENDA team
-
-
-
Manually annotated by BRENDA team
-
-
-
Manually annotated by BRENDA team
potato
-
-
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
evolution
-
CyB5R is a member of the NAD(P)H-ferredoxin reductase (FNR) enzyme superfamily, phylogenetic analysis
malfunction
metabolism
physiological function
additional information
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
1,2-dihydro-8-(4-methylpiperazin-1-yl)-4-phenylimidazol[3,2-e]pyrazine 5-oxide + NADH
1,2-dihydro-8-(4-methylpiperazin-1-yl)-4-phenylimidazol[3,2-e]pyrazine + NAD+
show the reaction diagram
-
potential bioreductive drug, trivial name RB90740
-
?
2 ferricyanide + NADH
2 ferrocyanide + NAD+ + H+
show the reaction diagram
2 ferricyanide + NADPH
2 ferrocyanide + NADP+ + H+
show the reaction diagram
2 ferricytochrome b5 + NADH
2 ferrocytochrome b5 + NAD+ + H+
show the reaction diagram
2 ferricytochrome b5 + NADPH
2 ferrocytochrome b5 + NADP+ + H+
show the reaction diagram
with NADPH the enzyme shows about 20% of the activity with NADH
-
-
?
2 ferricytochrome c + NADH
2 ferrocytochrome c + NAD+ + H+
show the reaction diagram
2-[4-iodophenyl]-3-[4-nitrophenyl]-5-[2,4-disulfophenyl]-2H tetrazolium monosodium salt + NADH
?
show the reaction diagram
-
-
-
?
5alpha-dihydrotestosterone + acceptor
?
show the reaction diagram
-
-
-
-
r
aquacobalamin + NADH
reduced aquacobalamin + NAD+
show the reaction diagram
-
in the presence of outer membrane cytochrome b, no activity with cyanocobalamin
-
?
benzamidoxime + NADH
?
show the reaction diagram
-
in the presence of cytochrome b5
-
-
?
Cu2+-citrate + NADH
Cu+-citrate + NAD+
show the reaction diagram
dapsone hydroxylamine + NADH
?
show the reaction diagram
-
in the presence of cytochrome b5
-
-
?
deoxyhemerythrin + O2
?
show the reaction diagram
-
-
-
-
?
Fe3+-ammonium sulfate + NADH
Fe2+-ammonium sulfate + NAD+
show the reaction diagram
-
strongly elevated by the addition of cytochrome b5
-
?
Fe3+-ATP + NADH
Fe2+-ATP + NAD+
show the reaction diagram
Fe3+-citrate + NADH
Fe2+-citrate + NAD+
show the reaction diagram
Fe3+-EDTA + NADH
Fe2+-EDTA + NAD+
show the reaction diagram
Fe3+-histidine + NADH
Fe2+-histidine + NAD+
show the reaction diagram
-
strongly elevated by the addition of cytochrome b5
-
?
Fe3+-nitrilotriacetate + NADH
Fe2+-nitrilotriacetate + NAD+
show the reaction diagram
-
in the presence of cytochrome b5, iron chelate reduction in descending order: Fe3+-nitrolotriacetate, Fe3+-ADP, Fe3+-diphosphate, Fe3+-citrate
-
?
ferricytochrome b5 + 4-(5-(4-[amino(hydroxyamino)methyl]phenyl)-2-furyl)-N'-hydroxybenzenecarboximidamide
ferrocytochrome b5 + ?
show the reaction diagram
-
metabolite of DB289, an antimicrobial prodrug of furamidine
-
-
?
ferricytochrome b5 + 4-(5-(4-[amino(hydroxyamino)methyl]phenyl)-2-furyl)-N'-methoxybenzenecarboximidamide
ferrocytochrome b5 + ?
show the reaction diagram
-
metabolite of DB289, an antimicrobial prodrug of furamidine
-
-
?
ferricytochrome b5 + N-hydroxy-2-amino-1-methyl-6-phenylimidazol[4,5-b]pyridine
ferrocytochrome b5 + ?
show the reaction diagram
-
arylhydroxylamine carcinogen found in grilled meat
-
-
?
ferricytochrome b5 + N-hydroxy-4-aminobiphenyl
ferrocytochrome b5 + ?
show the reaction diagram
-
arylhydroxylamine carcinogen found in cigarette smoke
-
-
?
lucigenin + NADH
?
show the reaction diagram
-
-
-
?
methemerythrin + NADH
deoxymethemerythrin + NAD+
show the reaction diagram
methemoglobin + NADH
hemoglobin + NAD+
show the reaction diagram
-
provides functional hemoglobin
-
-
?
methemoglobin-ferrocyanide complex + NADH
reduced methemoglobin-ferrocyanide complex + NAD+
show the reaction diagram
-
-
-
?
NADH + methemoglobin
NAD+ + hemoglobin
show the reaction diagram
-
-
-
-
?
sulfamethoxazole hydroxylamine + NADH
?
show the reaction diagram
-
in the presence of cytochrome b5
-
-
?
additional information
?
-
NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
2 ferricytochrome b5 + NADH
2 ferrocytochrome b5 + NAD+ + H+
show the reaction diagram
5alpha-dihydrotestosterone + acceptor
?
show the reaction diagram
-
-
-
-
r
benzamidoxime + NADH
?
show the reaction diagram
-
in the presence of cytochrome b5
-
-
?
dapsone hydroxylamine + NADH
?
show the reaction diagram
-
in the presence of cytochrome b5
-
-
?
deoxyhemerythrin + O2
?
show the reaction diagram
-
-
-
-
?
methemoglobin + NADH
hemoglobin + NAD+
show the reaction diagram
-
provides functional hemoglobin
-
-
?
NADH + methemoglobin
NAD+ + hemoglobin
show the reaction diagram
-
-
-
-
?
sulfamethoxazole hydroxylamine + NADH
?
show the reaction diagram
-
in the presence of cytochrome b5
-
-
?
additional information
?
-
COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Ca2+
-
2 mM, 23fold activation
Mg2+
-
half maximal activation at 1 mM
additional information
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
(+)-catechin
-
-
(+)-taxifolin
-
-
(-)-epicatechin
-
-
1,10-phenanthroline
-
-
2,2'-dipyridyl
-
-
5'-(p-fluorosulfonylbenzoyl)-adenosine
-
-
5-propyl-2-thiouracil
-
25 mM, almost complete inhibition
acetate
-
-
Acrynol
adenine nucleotides
apigenin
-
-
Atebrin
benzyl alcohol
-
100 mM, 52% inhibition, reversible, may be due to changes in membrane fluidity
Br-
-
competitive vs. cytochrome b5, reversible by dilution
CaCl2
-
8 mM, 50% inhibition, competitive vs. cytochrome b5
citrate
-
-
dicoumarol
F-
-
competitive vs. cytochrome b5, reversible by dilution
Hemin
-
-
I-
-
competitive vs cytochrome b5, reversible by dilution
Inositol hexaphosphate
-
-
iodoacetamide
-
1 mM, complete inhibition
iodoacetic acid
-
5 mM, complete inhibition
K+ high ionic strength
luteolin
-
-
luteolin-7-O-glucoside
-
-
Mepacrin
-
-
MgCl2
-
78.1 mM, 50% inhibition, competitive vs. cytochrome b5
morin
-
-
myricetin
N-ethylmaleimide
p-chloromercuribenzoate
p-hydroxymercuribenzoate
para-chloromercuribenzenesulfonate
-
Pentachlorophenol
-
-
phosphate
-
competitive inhibition
Phytohemagglutinin
-
-
-
Proflavin
quercetin
-
-
quercitrin
-
-
rutin
-
-
succinate
-
-
taurodeoxycholate
Thenoyltrifluoroacetone
-
-
Tris
-
reduction of cytochrome b5
Wheat germ agglutinin
-
-
-
additional information
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
9-Amino-1,2,3,4-tetrahydroacridine
-
activation
Detergents
spermine
-
activation
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.83
2,6-dichlorophenolindophenol
-
-
0.0419
aquacobalamin
-
-
0.63
benzamidoxime
-
pH 7.4
0.000007 - 0.08199
cytochrome b5
0.007
cytochrome c
-
cytochrome b5/cytochrome b5 reductase FAD-domain fusion protein
0.36
dapsone hydroxylamine
-
pH 7.4
0.0006 - 4.35
ferricyanide
0.01 - 0.013
ferricytochome b5
0.0008 - 0.125
ferricytochrome b5
0.001 - 0.107
ferrocytochrome b5
0.008
methemoglobin-ferrocyanide complex
-
-
-
0.25
N-hydroxy-2-amino-1-methyl-6-phenylimidazol[4,5-b]pyridine
-
pH 7.4
0.22
N-Hydroxy-4-aminobiphenyl
-
pH 7.4
0.00016 - 3.32
NADH
0.001 - 14
NADPH
0.36
sulfamethoxazole hydroxylamine
-
pH 7.4
0.025 - 0.089
testosterone
-
depending on phosphate concentration
additional information
additional information
-
detailed analysis of biphasic rate of reduction of cytochrome b5 in membranes. The initial rapid phase is completed within 10 msec and over 90% of cytochrome b5 are reduced in 40 msec. Evaluation of data in terms of two-dimensional random walk model
-
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
50.2
2,6-dichlorophenolindophenol
Musca domestica
-
-
1 - 877
cytochrome b5
8.3
cytochrome c
Rattus norvegicus
-
cytochrome b5/cytochrome b5 reductase FAD-domain fusion protein
12 - 1241
ferricyanide
33 - 417
ferricytochome b5
14 - 911
ferricytochrome b5
10 - 600
ferrocytochrome b5
0.733 - 1150
NADH
3 - 550
NADPH
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
25530 - 46610
ferricyanide
80700 - 120500
ferricytochrome b5
880 - 68320
NADH
Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.08
ADP
-
-
0.00021
myricetin
-
versus NADH, pH 7.5, 24-25C
additional information
additional information
-
inhibition kinetics
-
IC50 VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.0045
(+)-catechin
Bos taurus
-
pH 7.5, 22C
0.0098
(+)-taxifolin
Bos taurus
-
pH 7.5, 24-25C
0.0032
(-)-epicatechin
Bos taurus
-
pH 7.5, 22C
0.036
apigenin
Bos taurus
-
pH 7.5, 22C
0.00011
luteolin
Bos taurus
-
pH 7.5, 22C
0.0024
luteolin-7-O-glucoside
Bos taurus
-
pH 7.5, 22C
0.00081
morin
Bos taurus
-
pH 7.5, 22C
0.00037 - 0.0015
myricetin
0.0011
quercetin
Bos taurus
-
pH 7.5, 22C
0.0012
quercitrin
Bos taurus
-
pH 7.5, 22C
0.057
rutin
Bos taurus
-
pH 7.5, 22C
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0.00072
-
liver microsomes, reduction of 1,2-dihydro-8-(4-methylpiperazin-1-yl)-4-phenylimidazol[3,2-e]pyrazine 5-oxide
0.0039
-
activity in liver microsomes
0.036 - 0.109
-
activity in lysates of different cancer cell lines
0.0648
-
activity in liver microsomes in the presence of 2 mM MgCl2
0.0888
-
activity in liver microsomes in the presence of 2 mM CaCl2
0.109
-
reduction of aquacobalamin
0.372
-
in the presence of 0.1% Triton X-100
1.69
-
methemoglobin-ferrocyanide reductases assay
2.042
-
reduction of cytochrome b5
3.5
-
low MW aggregate, nitro blue tetrazolium as electron acceptor
10.6
-
low MW aggregate, cytochrome b as electron acceptor
14.9
-
pH 7.0, 25C, substrate ferricyanide
96.3
-
recombinant enzyme
137
-
-
138
-
low MW aggregate, dichlorophenolindophenol as electron acceptor
230.5
-
high MW aggregate
611.1
-
low MW aggregate, ferricyanide as electron acceptor
670
-
-
1007
-
reduction of ferricyanide
1200 - 1300
-
ferricyanide reduction
1400
-
recombinant enzyme
1470
-
enzyme from liver plasma membrane
1510
-
liver microsomal enzyme, ferricyanide as electron acceptor
2480
-
reduction of ferricyanide
additional information
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5 - 5.7
-
-
5.2
-
NADH-methemoglobin-ferrocyanide
5.5
-
acceptor ferricyanide
5.6
-
steady decrease above
5.7 - 8
-
rapid decrease above
6 - 8
-
acceptor Phascolopsis gouldii cytochrome b5
6
around, recombinant enzyme
6.4
-
citrate-phosphate buffer
6.5 - 8.5
-
NADH-ferricyanide
6.5
-
Tris-phosphate buffer
6.6 - 7.5
-
assay at
6.6
-
Tris-maleate buffer
6.8
-
reduction of cytochrome c
6.8 - 7.5
-
-
7 - 7.5
-
-
7
-
triethanolamine buffer
7.2 - 8.4
-
assay at, dependent on assay method
additional information
-
no distinct optimum with phosphate or Tris-HCl buffer
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5 - 8
-
depending on acceptor
6.6 - 7.5
-
enzyme activity is higher at pH 7.5 compared to pH 6.6
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
22
-
assay at room temperature
24 - 25
-
assay at
25
-
assay at
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
8.9
calculated from sequence
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
-
highest activity in confluently grown cells
Manually annotated by BRENDA team
-
transcripts of L, X and Y mRNAs are detected
Manually annotated by BRENDA team
-
transcripts of L, X and Y mRNAs are detected
Manually annotated by BRENDA team
-
transcripts of L, X, R and Y mRNAs are detected
Manually annotated by BRENDA team
developing seed; developing seed
Manually annotated by BRENDA team
additional information
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
-
soluble isozyme
Manually annotated by BRENDA team
additional information
-
possible conformation of membrane binding domain
-
Manually annotated by BRENDA team