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Information on EC 2.7.1.6 - galactokinase and Organism(s) Homo sapiens

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EC Tree
IUBMB Comments
Part of the Leloir pathway for galactose metabolism. The enzymes from mammals and from the bacterium Escherichia coli have no activity with N-acetyl-alpha-D-galactosamine [4-6].
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This record set is specific for:
Homo sapiens
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Word Map
The taxonomic range for the selected organisms is: Homo sapiens
The expected taxonomic range for this enzyme is: Eukaryota, Bacteria, Archaea
Synonyms
galactokinase, galk, galk1, gal1p, galactose kinase, atgalk, galactokinase 1, bigalk, galkspe4, galkamu, more
SYNONYM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
ATP:D-galactose-1-phosphotransferase
-
-
-
-
Gal1p
-
-
-
-
galactokinase
-
-
galactokinase 1
-
galactose kinase
-
-
-
-
kinase (phosphorylating), galacto-
-
-
-
-
kinase, galacto- (phosphorylating)
-
-
-
-
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
ATP + alpha-D-galactose = ADP + alpha-D-galactose 1-phosphate
show the reaction diagram
the most likely kinetic mechanism is an ordered ternary complex in which ATP is the first substrate to bind
-
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
phospho group transfer
-
-
-
-
SYSTEMATIC NAME
IUBMB Comments
ATP:D-galactose 1-phosphotransferase
Part of the Leloir pathway for galactose metabolism. The enzymes from mammals and from the bacterium Escherichia coli have no activity with N-acetyl-alpha-D-galactosamine [4-6].
CAS REGISTRY NUMBER
COMMENTARY hide
9030-53-9
-
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
ATP + 2-deoxy-D-galactose
ADP + 2-deoxy-alpha-D-galactose 1-phosphate
show the reaction diagram
ATP + 2-deoxy-D-galactose
ADP + 2-deoxy-D-galactose 1-phosphate
show the reaction diagram
-
-
-
?
ATP + alpha-D-galactose
ADP + alpha-D-galactose 1-phosphate
show the reaction diagram
ATP + D-galactosamine
ADP + alpha-D-galactosamine 1-phosphate
show the reaction diagram
-
-
-
?
ATP + D-galactosamine
ADP + D-galactosamine 1-phosphate
show the reaction diagram
-
-
-
?
ATP + D-galactose
ADP + alpha-D-galactose 1-phosphate
show the reaction diagram
ATP + D-talose
ADP + alpha-D-talose 1-phosphate
show the reaction diagram
ATP + galactose
ADP + alpha-D-galactose 1-phosphate
show the reaction diagram
additional information
?
-
-
no substrate: N-acetyl-D-galactosamine, L-arabinose, D-fucose, D-glucose
-
-
?
NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
ATP + alpha-D-galactose
ADP + alpha-D-galactose 1-phosphate
show the reaction diagram
ATP + galactose
ADP + alpha-D-galactose 1-phosphate
show the reaction diagram
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Ca2+
-
absolute requirement for a divalent cation, Ca2+ can be partially replaced by Co2+
Co2+
-
absolute requirement for a divalent cation, Mg2+ can be partially replaced by Co2+
Mg2+
-
absolute requirement for a divalent cation, maximally active in presence of 5 mM Mg2+
Mn2+
-
absolute requirement for a divalent cation, Mg2+ can be partially replaced by Co2+
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
2-(1,3-benzoxazol-2-ylamino)-4-(4-chloro-1H-pyrazol-3-yl)-4,6,7,8-tetrahydroquinazolin-5(1H)-one
-
inhibitory to isoform Galk1, no inhibition of isoform Galk2 up to 40 microM. Uncompetitive with respect to galactose, compound directly competes with ATP at the binding site, and galactose may be required to bind first. Compound is able to lower galactose 1-phosphate levels in primary fibroblasts of patients suffering Classic Galactosemia without significant effect on viability of cells
alpha-D-galactose 1-phosphate
D-galactose 1-phosphate
-
-
Hg2+
-
-
NEM
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1.0 mM, 41% inhibition
PCMB
-
1.0 mM, complete inhibition
Zn2+
-
-
additional information
-
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.3 - 7.4
2-deoxy-D-galactose
0.078 - 3.278
alpha-D-galactose
0.0024 - 34.5
ATP
0.22 - 4.8
D-galactosamine
0.1 - 13
D-galactose
0.37 - 2.3
D-talose
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.4 - 15
2-deoxy-D-galactose
0.7 - 12.9
alpha-D-galactose
0.2 - 25
ATP
0.2 - 25
D-galactosamine
0.4 - 8.7
D-galactose
0.2 - 18.1
D-talose
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.006 - 7.1
2-deoxy-D-galactose
2.4 - 25
alpha-D-galactose
17.6 - 3000
ATP
0.3 - 91
D-galactosamine
0.2 - 2.9
D-talose
Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
28 - 90
alpha-D-galactose 1-phosphate
2
D-galactose 1-phosphate
-
37°C
IC50 VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.0047
2-(1,3-benzoxazol-2-ylamino)-4-(4-chloro-1H-pyrazol-3-yl)-4,6,7,8-tetrahydroquinazolin-5(1H)-one
Homo sapiens
-
isoform Galk1, pH not specified in the publication, temperature not specified in the publication
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0.0812
-
-
0.15
-
-
1.62
-
enzyme from erythrocyte
1.737
-
enzyme from placenta
additional information
-
-
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
7.7 - 7.9
-
Tris-glycine-NaH2PO4 buffer
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5.8
-
isoelectric focusing
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
drug target
malfunction
galactosemia type 2 is an autosomal recessive disorder characterized by the deficiency of galactokinase enzyme due to missense mutations in GALK1 gene, which is associated with various manifestations such as hypergalactosemia and formation of cataracts. Systematically searched for the mutations that have been reported in the GALK1 protein that cause galactosemia type 2. Genetic variations form the basis of the evolution; however, not all genetic mutations are disease-causing
metabolism
the enzyme catalyses the first committed step in the Leloir pathway
UNIPROT
ENTRY NAME
ORGANISM
NO. OF AA
NO. OF TRANSM. HELICES
MOLECULAR WEIGHT[Da]
SOURCE
SEQUENCE
LOCALIZATION PREDICTION?
GALK1_HUMAN
392
0
42272
Swiss-Prot
other Location (Reliability: 3)
Q6ZP37_HUMAN
396
0
42952
TrEMBL
other Location (Reliability: 4)
E5LAN0_HUMAN
63
0
7033
TrEMBL
other Location (Reliability: 2)
D1MI96_HUMAN
63
0
7017
TrEMBL
other Location (Reliability: 2)
D0EM88_HUMAN
23
0
2442
TrEMBL
other Location (Reliability: 1)
C8CHJ5_HUMAN
49
0
5610
TrEMBL
Mitochondrion (Reliability: 4)
C8CHJ6_HUMAN
60
0
6748
TrEMBL
other Location (Reliability: 3)
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
26000
-
2 * 26000, SDS-PAGE
37000 - 38000
-
gel filtration
38000
-
1 * 38000, SDS-PAGE
53000 - 57000
-
gel filtration
55000
-
gel filtration
58000
-
gel filtration
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
dimer
monomer
-
1 * 38000, SDS-PAGE
CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
in complex with D-galactose and adenosine 5’-(beta,gamma-imino)-triphosphate
-
PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
A198V
A384P
-
mutant enzyme is not present in the soluble fraction after sonication and can not be purified
C32M
-
mutant enzyme is not present in the soluble fraction after sonication and can not be purified
D46A
-
no detectable activity
E174Q
no detectable activity, less stable enzyme
E244S
significantly increased (5fold) Michaelis constant for ATP, indicating that this variation impacts on the interaction of the protein with ATP. Significantly increased Michaelis constants for galactose. Turnover number is significantly increased
E245S
catalyzes less efficiently the phosphorylation of galactose than the wild-type enzyme. Significantly increased Michaelis constants for galactose. Turnover number is significantly increased
E43A
-
minor changes in kinetic parameters
E43G
-
10fold drop in turnover number
E43G/H44I
-
not soluble
G346S
-
mutant enzyme shows substantial reduction in turnover number. Lower specificity constant for galactose than wild-type enzyme
G347S
-
mutant enzyme shows substantial reduction in turnover number, increase in Km-value for galactose. Lower specificity constant for galactose than wild-type enzyme
G349S
G36R
-
mutant enzyme is not present in the soluble fraction after sonication and can not be purified
H44A
-
not soluble
H44I
-
not soluble
H44Y
-
increrase in Km-value for galactose compared to wild-type. Lower specificity constant for galactose than wild-type enzyme
L139P
a loss of stability and function is predicted by molecular docking and simulation modeling
L231S
catalyzes less efficiently the phosphorylation of galactose than the wild-type enzyme. Reduced turnover and decreased catalytic efficiency with the substrates 2-deoxy-D-galactose and ATP
M185L
statistically significantly increased catalytic turnover, with corresponding increases in the Michaelis constants for both substrates ATP and alpha-D-galactose. The specificity constants for galactose and ATP are not significantly changed. This variant is significantly less thermally stable than the wild-type protein and is less resistant to denaturation by urea
M60V/M180V
modest, but significant, increase in the melting temperature compared to the wild type, but no change in the turnover number
M60V/M180V/A334S
none of the steady state kinetic parameters is significantly altered. The variant has significantly increased thermal stability
M60V/M180V/A334S/D268E/G373S
increase in thermal stability, but no significant change in the kinetic parameters
M60V/M180V/A334S/G373S
increase in thermal stability, but no significant change in the kinetic parameters
M60V/M180V/D268E/A334S/R366Q/G373S
mutant enzyme with increased thermal stability and increased turnover towards some substrates. The conformation of the protein is altered at key sites. The number of salt bridges and hydrogen bonds is increased. More stable towards denaturation by urea
Q242S
the turnover number and the catalytic efficiency with ATP (cosubstrate 2-deoxy-D-galactose) are increased. Inactive with D-galactosamine. Turnover number is significantly increased
R105M
modest reduction in activity with little change in stability
R228M
interaction with both ATP and galactose is affected. The variant is significantly less stable than the wild-type protein
R256W
-
drastic reduction of activity when expressed in COS cells, missense mutation causes GALK deficiency
T288M
-
mutant enzyme is not present in the soluble fraction after sonication and can not be purified
T344M
-
drastic reduction of activity when expressed in COS cells, missense mutation causes GALK deficiency
Y379W
a variant with greater substrate promiscuity than wild-type enzyme
additional information
-
the two deletions, of 410delG and 509-510delGT , occur at the nucleotide repeats GGGGGG and GTGTGT, respectively and result in in-frame nonsense codons at amino acids 163 and 201. These mutations arise by slipped strand mispairing
TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
30
-
10 min, no loss of activity
50
-
10 min, 25% loss of activity
50.33
Tm-value, mutant enzyme M185L/Y379W
50.51
Tm-value, mutant enzyme M185L
51.3
Tm-value, mutant enzyme R228K
51.68
Tm-value, mutant enzyme R228M
52.07
Tm-value, mutant enzyme Y379W
52.31
52.5
Tm-value, mutant enzyme E174Q
52.7
Tm-value, mutant enzyme Q242S
53.83
Tm-value, mutant enzyme M60V/M185L/M180V/D268E/A334S/R366Q/G373S/Y379W
54
Tm-value, mutant enzyme E245S
54.41
Tm-value, mutant enzyme A334S
55.01
Tm-value, mutant enzyme G373S
55.1
Tm-value, mutant enzyme E244S
55.13
Tm-value, mutant enzyme E174D
55.17
Tm-value, mutant enzyme M180V
55.42
Tm-value, mutant enzyme R105M
55.72
Tm-value, wild-type enzyme
55.74
Tm-value, wild type enzyme
55.8
Tm-value, mutant enzyme L231S
55.81
Tm-value, mutant enzyme R366Q
55.93
Tm-value, mutant enzyme M60V
56.1
Tm-value, wild-type enzyme
57.14
Tm-value, mutant enzyme M60V/M180V/D268E/A334S/R366Q/G373S/Y379W
57.7
Tm-value, mutant enzyme M60V/M180V
58.08
Tm-value, mutant enzyme M180V/M60V/A334S
58.09
Tm-value, mutant enzyme M180V/M60V/A334S/G373S/D268E
58.11
Tm-value, mutant enzyme M180V/M60V/A334S/G373S
58.12
Tm-value, mutant enzyme M60V/M180V/A334S/D268E/R336Q/G373S
60
-
10 min, 60% loss of activity
GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
dithiothreitol protects the enzyme better than 2-mercaptoethanol against denaturation on storage at 4°C
-
ORGANIC SOLVENT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
-20°C, unstable in 0.01 M KH2PO4-K2HPO4, pH 7.2 buffer, 0.01 M MgCl2, 1 mM dithiothreitol, 0.2 mM ATP without glycerol
-
4°C, 0.01 M KH2PO4-K2HPO4, pH 7.2 buffer, 0.01 M MgCl2, 1 mM dithiothreitol, about 40% loss of activity after 24 h
-
4°C, 3.0 M ammonium sulfate, 10% loss of activity after 6 d
-
PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
recombinant enzyme
-
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
expression in COS7 cells
expression in Escherichia coli
-
expression in Escherichia coli HMS174(DE3)
mutant and wild-type cDNA introduced into COS cells
-
EXPRESSION
ORGANISM
UNIPROT
LITERATURE
enhanced gene expression caused by a nucleotide variation within GALKI promoter (c.-22T>C mutation)
-
APPLICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
medicine
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Blume, K.G.; Beutler, E.
Galactokinase from human erythrocytes
Methods Enzymol.
42C
47-53
1975
Homo sapiens
-
Manually annotated by BRENDA team
Blume, K.G.; Beutler, E.
Purification and properties of galactokinase from human red blood cells
J. Biol. Chem.
246
6507-6510
1971
Homo sapiens
Manually annotated by BRENDA team
Stambolian, D.; Scarpino-Myers, V.; Harris, H.
Purification of human galactokinase and evidence for its existence as a monomer form
Biochim. Biophys. Acta
831
306-312
1985
Homo sapiens
Manually annotated by BRENDA team
Srivastava, S.K.; Blume, K.G.; Van Loon, C.; Beutler, E.
Purification and kinetic properties of galactokinase from human placenta
Arch. Biochem. Biophys.
150
191-198
1972
Homo sapiens
Manually annotated by BRENDA team
Asada, M.; Okano, Y.; Imamura, T.; Suyama, I.; Hase, Y.; Isshiki, G.
Molecular characterization of galactokinase deficiency in Japanese patients
J. Hum. Genet.
44
377-382
1999
Homo sapiens
Manually annotated by BRENDA team
Okano, Y.; Asada, M.; Fujimoto, A.; Ohtake, A.; Murayama, K.; Hsiao, K.J.; Choeh, K.; Yang, Y.; Cao, Q.; Reichardt, J.K.; Niihira, S.; Imamura, T.; Yamano, T.
A genetic factor for age-related cataract: identification and characterization of a novel galactokinase variant, Osaka, in asians
Am. J. Hum. Genet.
68
1036-1042
2001
Homo sapiens
Manually annotated by BRENDA team
Timson, D.J.; Reece, R.J.
Functional analysis of disease-causing mutations in human galactokinase
Eur. J. Biochem.
270
1767-1774
2003
Homo sapiens
Manually annotated by BRENDA team
Timson, D.J.; Reece, R.J.
Sugar recognition by human galactokinase
BMC Biochem.
4
16
2003
Homo sapiens
Manually annotated by BRENDA team
Thoden, J.B.; Timson, D.J.; Reece, R.J.; Holden, H.M.
Molecular structure of human galactokinase: implications for type II galactosemia
J. Biol. Chem.
280
9662-9670
2005
Homo sapiens
Manually annotated by BRENDA team
Wierenga, K.J.; Lai, K.; Buchwald, P.; Tang, M.
High-throughput screening for human galactokinase inhibitors
J. Biomol. Screen.
13
415-423
2008
Homo sapiens
Manually annotated by BRENDA team
Park, H.D.; Bang, Y.L.; Park, K.U.; Kim, J.Q.; Jeong, B.H.; Kim, Y.S.; Song, Y.H.; Song, J.
Molecular and biochemical characterization of the GALK1 gene in Korean patients with galactokinase deficiency
Mol. Genet. Metab.
91
234-238
2007
Homo sapiens (P51570), Homo sapiens
Manually annotated by BRENDA team
Park, H.; Kim, Y.; Park, K.; Kim, J.; Song, Y.; Song, J.
A novel c.-22T>C mutation in GALK1 promoter is associated with elevated galactokinase phenotype
BMC Med. Genet.
10
29
2009
Homo sapiens
Manually annotated by BRENDA team
Liu, L.; Tang, M.; Walsh, M.J.; Brimacombe, K.R.; Pragani, R.; Tanega, C.; Rohde, J.M.; Baker, H.L.; Fernandez, E.; Blackman, B.; Bougie, J.M.; Leister, W.H.; Auld, D.S.; Shen, M.; Lai, K.; Boxer, M.B.
Structure activity relationships of human galactokinase inhibitors
Bioorg. Med. Chem. Lett.
25
721-727
2015
Homo sapiens
Manually annotated by BRENDA team
McAuley, M.; Huang, M.; Timson, D.J.
Insight into the mechanism of galactokinase Role of a critical glutamate residue and helix/coil transitions
Biochim. Biophys. Acta Proteins Proteom.
1865
321-328
2017
Homo sapiens (P51570), Homo sapiens
Manually annotated by BRENDA team
McAuley, M.; Huang, M.; Timson, D.J.
Modulation of the mobility of a key region in human galactokinase Impacts on catalysis and stability
Bioorg. Chem.
81
649-657
2018
Homo sapiens (P51570), Homo sapiens
Manually annotated by BRENDA team
McAuley, M.; Mesa-Torres, N.; McFall, A.; Morris, S.; Huang, M.; Pey, A.L.; Timson, D.J.
Improving the activity and stability of human galactokinase for therapeutic and biotechnological applications
ChemBioChem
19
1088-1095
2018
Homo sapiens (P51570), Homo sapiens
Manually annotated by BRENDA team
P, S.; Ebrahimi, E.A.; Ghazala, S.A.; D, T.K.; R, S.; Priya Doss C, G.; Zayed, H.
Structural analysis of missense mutations in galactokinase 1 (GALK1) leading to galactosemia type-2
J. Cell. Biochem.
119
7585-7598
2018
Homo sapiens (P51570), Homo sapiens
Manually annotated by BRENDA team
Hu, X.; Zhang, Y.Q.; Lee, O.W.; Liu, L.; Tang, M.; Lai, K.; Boxer, M.B.; Hall, M.D.; Shen, M.
Discovery of novel inhibitors of human galactokinase by virtual screening
J. Comput. Aided Mol. Des.
33
405-417
2019
Homo sapiens (P51570), Homo sapiens
Manually annotated by BRENDA team