Information on EC 2.4.2.44 - S-methyl-5'-thioinosine phosphorylase

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The expected taxonomic range for this enzyme is: Pseudomonas aeruginosa

EC NUMBER
COMMENTARY
2.4.2.44
-
RECOMMENDED NAME
GeneOntology No.
S-methyl-5'-thioinosine phosphorylase
-
REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
S-methyl-5'-thioinosine + phosphate = hypoxanthine + S-methyl-5-thio-alpha-D-ribose 1-phosphate
show the reaction diagram
-
-
-
-
PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
S-methyl-5'-thioadenosine degradation III
-
-
SYSTEMATIC NAME
IUBMB Comments
S-methyl-5'-thioinosine:phosphate S-methyl-5-thio-alpha-D-ribosyl-transferase
No activity with S-methyl-5'-thioadenosine. The catabolism of of 5'-methylthioadenosine in Pseudomonas aeruginosa involves deamination to S-methyl-5'-thioinosine (EC 3.5.4.31, S-methyl-5'-thioadenosine deaminase) and phosphorolysis to hypoxanthine [1].
SYNONYMS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
methylthioinosine phosphorylase
-
MTI phosphorylase
-
ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
SUBSTRATE
PRODUCT                      
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
5'-methylthioinosine + phosphate
hypoxanthine + 5-methylthio-D-ribose 1-phosphate
show the reaction diagram
-
-
?
adenosine + phosphate
adenine + alpha-D-ribose 1-phosphate
show the reaction diagram
weak substrate
-
?
adenosine + phosphate
adenine + D-ribose 1-phosphate
show the reaction diagram
-
-
?
inosine + phosphate
hypoxanthine + alpha-D-ribose 1-phosphate
show the reaction diagram
the catalytic efficiency (kcat/Km) for S-methyl-5'-thioinosine is 290 times larger than for inosine
-
?
S-methyl-5'-thioinosine + phosphate
hypoxanthine + S-methyl-5-thio-alpha-D-ribose 1-phosphate
show the reaction diagram
the enzyme is involved in catabolism of 5'-methylthioadenosine in Pseudomonas aeruginosa. S-Methyl-5'-thioadenosine is converted to S-methyl-5'-thioinosine and hypoxanthine but not to adenine
-
?
S-methyl-5'-thioinosine + phosphate
hypoxanthine + S-methyl-5-thio-alpha-D-ribose 1-phosphate
show the reaction diagram
the methylthio group of S-methyl-5'-thioinosine is important for both substrate binding and catalysis
-
?
inosine + phosphate
hypoxanthine + D-ribose 1-phosphate
show the reaction diagram
-
-
?
additional information
?
-
S-methyl-5'-thioadenosine is not a substrate
-
-
-
NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
S-methyl-5'-thioinosine + phosphate
hypoxanthine + S-methyl-5-thio-alpha-D-ribose 1-phosphate
show the reaction diagram
Q9HZK1
the enzyme is involved in catabolism of 5'-methylthioadenosine in Pseudomonas aeruginosa. S-Methyl-5'-thioadenosine is converted to S-methyl-5'-thioinosine and hypoxanthine but not to adenine
-
?
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
5'-methylthio-4'-deaza-1'-aza-2'-deoxy-1'-(9-methylene)-immucillin-H
-
5'-methylthio-immucillin-H
-
-
5'-phenylthio-immucillin-H
-
S-methyl-5'-thioadenosine
competitive inhibitor
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.0026
5'-methylthioinosine
pH 7.4, 25C
0.023
adenine
pH 7.4, 25C
0.023
adenosine
pH 7.4, 25C
0.09
Inosine
pH 7.4, 25C
0.0026
S-methyl-5'-thioinosine
pH 7.4, 25C
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
4.8
5'-methylthioinosine
Pseudomonas aeruginosa
Q9HZK1
pH 7.4, 25C
0.0549
adenine
Pseudomonas aeruginosa
Q9HZK1
pH 7.4, 25C
0.0549
adenosine
Pseudomonas aeruginosa
Q9HZK1
pH 7.4, 25C
0.57
Inosine
Pseudomonas aeruginosa
Q9HZK1
pH 7.4, 25C
4.8
S-methyl-5'-thioinosine
Pseudomonas aeruginosa
Q9HZK1
pH 7.4, 25C
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.24
adenine
Pseudomonas aeruginosa
Q9HZK1
pH 7.4, 25C
144
6.3
Inosine
Pseudomonas aeruginosa
Q9HZK1
pH 7.4, 25C
167
1846
S-methyl-5'-thioinosine
Pseudomonas aeruginosa
Q9HZK1
pH 7.4, 25C
19238
Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.00000034
5'-methylthio-4'-deaza-1'-aza-2'-deoxy-1'-(9-methylene)-immucillin-H
pH 7.4, 25C
0.0000008
5'-methylthio-4'-deaza-1'-aza-2'-deoxy-1'-(9-methylene)-immucillin-H
pH 7.4, 25C
0.000000076
5'-methylthio-immucillin-H
pH 7.4, 25C
-
0.00000084
5'-methylthio-immucillin-H
pH 7.4, 25C
-
0.000000035
5'-phenylthio-immucillin-H
pH 7.4, 25C
0.00000066
5'-phenylthio-immucillin-H
pH 7.4, 25C
0.07
S-methyl-5'-thioadenosine
pH 7.4, 25C
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
homotrimer
crystal structure
trimer
the crystal structure in complex with hypoxanthine, determined to 2.8 A resolution reveals a 3-fold symmetric homotrimer
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
crystallization of recombinant enzyme (9 mg/ml) in 50 mM HEPES, pH 7.4, 30% polyethylene glycol monomethyl ether 2000, 0.1 M potassium thiocyanate in the presence of 5 mM S-methyl-5'-thioinosine and 5 mM sulfate by sitting-drop vapor diffusion. Crystal structure of the enzyme in complex with hypoxanthine is determined to 2.8 A resolution; the crystal structure of P. aeruginosa MTIP (PaMTIP) in complex with hypoxanthine is determined to 2.8 A resolution and reveals a three-fold symmetric homotrimer
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
; expressed in Escherichia coli as a His-tagged fusion protein