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Enzyme Nomenclature
Information on EC 2.1.1.158 - 7-methylxanthosine synthase
for references in articles please use BRENDA:EC2.1.1.158
Word Map on EC 2.1.1.158
- 2.1.1.158
-
n-methylation
-
methylase
- phenylethanolamine
- s-adenosyl-l-homocysteine
-
indolethylamine
- adomet
-
prmts
- coffea
- theobromine
-
s-adenosylmethionine-dependent
- phosphatidyl-n,n-dimethylethanolamine
- protein-arginine
-
s-adenosyl-l-methionine-dependent
- guanidinoacetate
- phosphatidyl-n-monomethylethanolamine
-
dopamine-derived
-
histone-specific
- agriculture
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The enzyme appears in viruses and cellular organisms
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EC NUMBER 
COMMENTARY 
2.1.1.158
-
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RECOMMENDED NAME
GeneOntology No.
7-methylxanthosine synthase
-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
S-adenosyl-L-methionine + xanthosine = S-adenosyl-L-homocysteine + 7-methylxanthosine
; The enzyme is specific for xanthosine, as XMP and xanthine cannot act as substrates [2,4]. The enzyme does not have N1- or N3- methylation activity. This is the first methylation step in the production of caffeine.
-
-
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S-adenosyl-L-methionine + xanthosine = S-adenosyl-L-homocysteine + 7-methylxanthosine
a catalytic residue is Gln161, cosubstrate and substrate binding site structures involving the Ser316 for xanthosine recognition, overview
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
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SYSTEMATIC NAME
IUBMB Comments
S-adenosyl-L-methionine:xanthosine N7-methyltransferase
The enzyme is specific for xanthosine, as XMP and xanthine cannot act as substrates [2,4]. The enzyme does not have N1- or N3- methylation activity [2]. This is the first methylation step in the production of caffeine.
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CAS REGISTRY NUMBER
COMMENTARY
192827-92-2
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
gene CaMTL3, enzyme XMT1; var. caturra, two different N-methyltransferases XMT and MXMT
SwissProt
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
metabolism
metabolism
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methylation of xanthosine by 7-methylxanthosine synthase is the most plausible rate-limiting step of caffeine biosynthesis, the supply of non-methylated purine precursors or availability of S-adenosyl-L-methionine are not the principal controlling factors of caffeine biosynthesis
metabolism
Coffea sp.
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the enzyme catalyzes the first step in caffeine biosynthesis, pathway overview
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
the enzyme is part of a caffeine biosynthetic pathway which includes a recycling of adenosine released from S-adenosyl-L-methionine in form of xanthosine monophosphate, overview
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-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
first step in caffeine biosynthesis
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
first step in caffeine biosynthesis pathway from xanthosine
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
first step in caffeine biosynthesis pathway from xanthosine
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-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
first step in caffeine biosynthesis pathway from xanthosine, reduction of the second enzyme of the pathway, 7-methylxanthine methyltransferase, EC 2.1.1.159, leads to reduced XMT1 expression
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ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
in vivo feeding experiments with radio-labeled substrate, product determination, overview
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-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
step of the caffeine biosynthesis, caffeine accumulation in seeds
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
specific methylation at N-7 position
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-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
the enzyme is specific for xanthosine
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-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
first step in caffeine biosynthesis pathway from xanthosine, reduction of the second enzyme of the pathway, 7-methylxanthine methyltransferase, EC 2.1.1.159, leads to reduced XMT1 expression
-
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ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
step of the caffeine biosynthesis, caffeine accumulation in seeds
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
step of the caffeine biosynthesis, caffeine accumulation in seeds
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
Coffea sp.
-
-
-
-
?
additional information
?
-
enzyme expression and activity during caffeine biosynthesis in fruits, overview
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-
-
additional information
?
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substrate specificity of the recombinant His-tagged enzyme, no activity with xanthosine 5'-phosphate, theobromine, or 7-methylxanthosine
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-
-
additional information
?
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-
enzyme expression and activity during caffeine biosynthesis in fruits, overview
-
-
-
additional information
?
-
-
enzyme expression and activity during caffeine biosynthesis in fruits, overview
-
-
-
additional information
?
-
Coffea sp.
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7-methylxanthosine synthase shows the most critical substrate specifi city of the three types of N-methyltransferases in Coffea species
-
-
-
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
the enzyme is part of a caffeine biosynthetic pathway which includes a recycling of adenosine released from S-adenosyl-L-methionine in form of xanthosine monophosphate, overview
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
Q9AVK0
-
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
Q9AVK0
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-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
-
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
first step in caffeine biosynthesis
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
first step in caffeine biosynthesis pathway from xanthosine
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
Q9AVK0
first step in caffeine biosynthesis pathway from xanthosine
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
Q9AVK0
first step in caffeine biosynthesis pathway from xanthosine, reduction of the second enzyme of the pathway, 7-methylxanthine methyltransferase, EC 2.1.1.159, leads to reduced XMT1 expression
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
in vivo feeding experiments with radio-labeled substrate, product determination, overview
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
Q9AVK0
step of the caffeine biosynthesis, caffeine accumulation in seeds
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
A4GE69
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-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
first step in caffeine biosynthesis pathway from xanthosine, reduction of the second enzyme of the pathway, 7-methylxanthine methyltransferase, EC 2.1.1.159, leads to reduced XMT1 expression
-
-
ir
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
step of the caffeine biosynthesis, caffeine accumulation in seeds
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
-
step of the caffeine biosynthesis, caffeine accumulation in seeds
-
-
?
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
Coffea sp.
-
-
-
-
?
additional information
?
-
Q9AVK0
enzyme expression and activity during caffeine biosynthesis in fruits, overview
-
-
-
additional information
?
-
-
enzyme expression and activity during caffeine biosynthesis in fruits, overview
-
-
-
additional information
?
-
-
enzyme expression and activity during caffeine biosynthesis in fruits, overview
-
-
-
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Mg2+
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
additional information
-
in vivo activities after feeding of radiolabeled L-methionine, activity profile of the enzyme in young, adult, and aged leaves, overview
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
7.5
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
27
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pI VALUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
additional information
-
high expression level in immature fruits, low expression in mature fruits
immature, ripening, and mature, enzyme expression and activity during development, overview
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immature, ripening, and mature, enzyme expression and activity during development, overview
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immature, ripening, and mature, enzyme expression and activity during development, overview
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activity profile of the enzyme in young, adult, and aged leaves, high activity in young leaves
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very high expression in young leaves, moderate expression in expanded leaves
additional information
method development for somatic embryogenesis, overview
additional information
-
method development for somatic embryogenesis, overview
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
-
co-localization of xanthosine methyltransferase, 7-methylxanthine methyltransferase, and 3,7-dimethylxanthine methyltransferase
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MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
42000
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SUBUNITS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
dimer
dimer
-
bimolecular fluorescence complementation. Enzymes xanthosine methyltransferase, 7-methylxanthine methyltransferase, and 3,7-dimethylxanthine methyltransferase each form a homo-dimer in cytosol. In addition, each enzyme also forms a hetero-dimer with each of the other two enzymes in cytosol
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Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
purified recombinant wild-type and selenomethionine-labeled XMT, 23-28% PEG 3350, 0.2 M LiCl, 0.1 M Tris-HCl, pH 8.5-8.7, 2 mM DTT, 1 mM S-adenosyl-L-cysteine, and 1 mM xanthosine, 1-3 days, 20°C, X-ray diffraction structure determination and analysis at 2.8-3.0 A resolution
purified recombinant wild-type and selenomethionine-labeled XMT, 23-28% PEG 3350, 0.2 M LiCl, 0.1 M Tris-HCl, pH 8.5-8.7, 2 mM DTT, 2 mM S-adenosyl-L-cysteine, and 2 mM xanthosine, 1-3 days, 20°C, plate-like crystals, X-ray diffraction structure determination and analysis at 2.2 A resolution
using Linbro plates and the conventional hanging-drop technique, in the presence of the demethylated cofactor S-adenosyl-l-cysteine or xanthosine
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
native enzyme 9fold from young leaves by 3 steps of ion exchange chromatography, and gel filtration
-
native enzyme partially from young leaves by ammonium sulfate fractionation, gel filtration, and ultrafiltration
-
recombinant His-tagged XMT1 from Escherichia coli strain BL21(DE3) to homogeneity by nickel affinity chromatography, cleavage of the His-tag with tobacco etch virus, TEV, protease, followed by gel filtration
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expression of wild-type and mutant enzymes in Escherichia coli strain BL21 (DE3), sequence comparison of caffeine synthetic enzymes from coffee
Coffea sp.
-
gene CaMTL3, cDNA library construction, DNA and amino acid sequence determination and analysis, sequence comparison with other species
gene CtCS1 or CaXMT1 or CmXRS1, DNA sequence determination, phylogenetic tree, expression in Escherichia coli strain BL21(DE3)
gene XMT1, DNA and amino acid sequence determination and analysis, expression analysis
isozyme XMT1, DNA and amino acid sequence determination and analysis, phylogenetic analysis, expression of the GST-tagged enzyme in Escherichia coli Bl21(DE3)
-
isozyme XMT1, functional expression in transgenic Nicotiana tabacum plant leaves
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
A23S
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
A23S/L191P/H219R
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
A23S/P104Q/H219R
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
A23S/P104Q/Q161H/H219R
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows 60% of wild-type 7-methylation activity
A23S/P104Q/Q161H/L191P/H219R
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
A23S/Q161H/H219R
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
A23S/Q161H/L191P/H219R
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
H219R
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
L191P
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
P104Q
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
P104Q/L191P
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
P104Q/Q161H
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
P104Q/Q161H/L191P
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
Q161H
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
Q161H/L191P
Coffea sp.
-
site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
additional information
additional information
reduction of the second enzyme of the pathway, 7-methylxanthine methyltransferase, EC 2.1.1.159, leads to reduced XMT1 expression
additional information
-
transgenic Nicotiana tabacum plant leaves expressing all three enzymes required for the biosynthesis of caffeine are no longer eaten by the tobacco cutworm caterpillars, Spodoptera litura, overview
additional information
-
reduction of the second enzyme of the pathway, 7-methylxanthine methyltransferase, EC 2.1.1.159, leads to reduced XMT1 expression
additional information
Coffea sp.
-
construction of several enzyme mutants, overview. The mutants of CmXRS1, that have 3-N methylation activity and produce caffeine from paraxanthine as a substrate, need to have replacement of the glutamine residue by histidine at position 161 in the CmXRS1 sequence, i.e. a Q161H mutation, overview
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APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
agriculture
-
expression of the caffeine biosynthesis enzymes in transgenic crop plants amay protect against the crop damaging larvae of pests
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LINKS TO OTHER DATABASES (specific for EC-Number 2.1.1.158)
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