Literature summary for 5.1.3.19 extracted from

Pacheco, B.; Maccarana, M.; Goodlett, D.R.; Malmstroem, A.; Malmstroem, L.
Identification of the active site of DS-epimerase 1 and requirement of N-glycosylation for enzyme function (2009), J. Biol. Chem., 284, 1741-1747.

Search for more literature for 5.1.3.19

Cloned(Commentary)

Cloned (Comment)	Organism
expression of wild-type and mutant enzymes in HEK-293 cells	Homo sapiens

Protein Variants

Protein Variants	Comment	Organism
H205A	site-directed mutagenesis of the catalytic site residue, the mutant shows complete loss of epimerase activity	Homo sapiens
H450A	site-directed mutagenesis of the catalytic site residue, the mutant shows complete loss of epimerase activity	Homo sapiens
N183S	site-directed mutagenesis of an N-glycosylation site in DS-epi1 altering reaction kinetics	Homo sapiens
N336S	site-directed mutagenesis of an N-glycosylation site in DS-epi1 altering reaction kinetics and reducing the activity 13fold	Homo sapiens
N642S	site-directed mutagenesis of an N-glycosylation site in DS-epi1 altering reaction kinetics	Homo sapiens
N648S	site-directed mutagenesis of an N-glycosylation site in DS-epi1 altering reaction kinetics and reducing the activity 43fold	Homo sapiens
Y261A	site-directed mutagenesis of the catalytic site residue, the mutant shows complete loss of epimerase activity	Homo sapiens

KM Value [mM]

KM Value [mM]	KM Value Maximum [mM]	Substrate	Comment	Organism	Structure
0.0049	-	D-glucuronate	pH 5.5, 37°C, recombinant mutant N648S	Homo sapiens
0.014	-	D-glucuronate	pH 5.5, 37°C, recombinant mutant N336S	Homo sapiens
0.016	-	D-glucuronate	pH 5.5, 37°C, recombinant mutant N183S	Homo sapiens
0.016	-	D-glucuronate	pH 5.5, 37°C, recombinant mutant N642S	Homo sapiens
0.024	-	D-glucuronate	ph 5.5, 37°C, recombinant wild-type enzyme	Homo sapiens

Organism

Organism	UniProt	Comment	Textmining
Homo sapiens	Q9UL01	-	-

Posttranslational Modification

Posttranslational Modification	Comment	Organism
glycoprotein	proper N-glycosylation of DS-epimerase 1 is required for enzyme activity	Homo sapiens

Reaction

Reaction	Comment	Organism	Reaction ID
Chondroitin D-glucuronate = dermatan L-iduronate	His-450 functions as a general base abstracting the C5 proton from glucuronic acid. Subsequent cleavage of the glycosidic linkage by Tyr-261 generates a 4,5-unsaturated hexuronic intermediate, which is protonated at the C5 carbon by His-205 from the side of the sugar plane opposite to the side of previous proton abstraction. Concomitant recreation of the glycosidic linkage ends the reaction, generating iduronic acid, proposed molecular mechanism of epimerization, overview	Homo sapiens	a

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
D-glucuronate	-	Homo sapiens	L-iduronate	-	?
additional information	identification of the catalytic site, and of three putative catalytic residues in DS-epimerase 1, His205, Tyr261, and His450, by tertiary structure modeling and amino acid conservation to heparinase II	Homo sapiens	?	-	?

Synonyms

Synonyms	Comment	Organism
DS-epimerase 1	-	Homo sapiens

Temperature Optimum [°C]

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

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
5.5	-	assay at	Homo sapiens

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Release 2023.1 (January 2023)