The main products of hydrolysis are iota-neocarratetraose sulfate and iota-neocarrahexaose sulfate. iota-Neocarraoctaose is the shortest substrate oligomer that can be cleaved. Unlike EC 3.2.1.81, beta-agarase and EC 3.2.1.83, kappa-carrageenase, this enzyme proceeds with inversion of the anomeric configuration. iota-Carrageenan differs from kappa-carrageenan by possessing a sulfo group on O-2 of the 3,6-anhydro-D-galactose residues, in addition to that present in the kappa-compound on O-4 of the D-galactose residues.
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Endohydrolysis of (1->4)-beta-D-linkages between D-galactose 4-sulfate and 3,6-anhydro-D-galactose-2-sulfate in iota-carrageenans
the enzyme hydrolyses the beta-(1->4) linkages in iota-carrageenans to produce a series of homologous, even-numbered oligosaccharides. The cleavage of glycosidic linkage catalyzed by iota-carrageenases also involves carboxylic acid-containing amino acid residues but, in contrast to kappa-carrageenases, it occurs via a direct, single displacement reaction by a water molecule, so that the configuration in the anomeric position is inverted
The main products of hydrolysis are iota-neocarratetraose sulfate and iota-neocarrahexaose sulfate. iota-Neocarraoctaose is the shortest substrate oligomer that can be cleaved. Unlike EC 3.2.1.81, beta-agarase and EC 3.2.1.83, kappa-carrageenase, this enzyme proceeds with inversion of the anomeric configuration. iota-Carrageenan differs from kappa-carrageenan by possessing a sulfo group on O-2 of the 3,6-anhydro-D-galactose residues, in addition to that present in the kappa-compound on O-4 of the D-galactose residues.
kappa-, iota- and lambda-carrageenase display strict specificity for their substrates, namely kappa-, iota- and lambda-carrageenans, respectively. The enzymes discriminate the substrate probably by recognizing the sulfation pattern of the digalactose reapeting unit of the polysaccharide. iota-Carrageenas present conserved arginine residues in the catalytic site which are believed to interact with carrageenans in which both sugar residues in the disaccharide units are negatively charged
analysis of hydrolysis products by thin layer chromatography, the endohydrolytic activity produces low molecular weight iota-carrageenan oligomers. The oligosaccharides observed include iota-carrageenan disaccharide (Dp2), tetrasaccharide (Dp4), and hexasaccharide (Dp6)
kappa-, iota- and lambda-carrageenase display strict specificity for their substrates, namely kappa-, iota- and lambda-carrageenans, respectively. The enzymes discriminate the substrate probably by recognizing the sulfation pattern of the digalactose reapeting unit of the polysaccharide. iota-Carrageenas present conserved arginine residues in the catalytic site which are believed to interact with carrageenans in which both sugar residues in the disaccharide units are negatively charged
the enzyme requires the Na+ ion for full activity, maximal activity is observed in the presence of 0.1 M NaCl. In buffer containing 10 mM NaCl, the enzyme activity decreases to 28% during 16 h incubation on ice
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DISEASE
TITLE OF PUBLICATION
LINK TO PUBMED
Insulin Resistance
?-Carrageenan Tetrasaccharide from ?-Carrageenan Inhibits Islet ? Cell Apoptosis Via the Upregulation of GLP-1 to Inhibit the Mitochondrial Apoptosis Pathway.
the most important types of commercial carrageenans, namely kappa-, iota- and lambda-carrageenan, are esterified with one, two, and three sulfate groups per repeating disaccharide unit, being also called carrageenose 4'-sulfate, carrageenose 2,4'-disulfate, and carrageenose 2,6,2'-trisulfate, respectively. kappa-Carrageenans occur in the cell wall of some species of marine red algae, such as Chondrus sp., Gigartina sp., Eucheuma sp. and Iridaea sp. but is mostly extracted from tropical seaweed Euchema cottoni (also known as Kappaphycus alvarezii), while iota-carrageenans are mainly extracted from Eucheuma spinosum (also known as Eucheuma denticulatum). Because kappa- and iota-carrageenans are produced from my- and ny-carrageenans, respectively, during the extraction under alkaline at high temperatures or biosynthetically by a reaction catalyzed by the enzyme sulfohydrolase, these polysaccharides are often found in commercial samples. lambda-Carrageenans are extracted from red algae within the Gigartina and Chondrus genera, which produces this type of polysaccharide during the sporophytic stage. These algae are also a source of kappa- and iota-carrageenans when they are in the gametophytic stage, but because they produce mixed chain polysaccharide chains containing both kappa- and iota-units, extraction of kappa- and iota-carrageenans from the mentioned algae is preferred. Carrageenan classes based on the number and position of sulfate groups in the chain, overview. The sulfate and AD contents of commercial kappa-, iota-, and lambda-carrageenans have been determined by acid hydrolysis, infrared spectroscopy, and nuclear magnetic resonance (NMR) analyses and found to be, respectively, 25-30 and 28-35% for the kappa-type, 28-30 and 25-30% for iota-type and 32-39% and 0 for lambda-type, respectively
the enzyme belongs to the glycoside hydrolases family 82, GH 82. In spite of having specificities for structure-related substrates, kappa-, iota- and lambda-carrageenases do not share significant sequence homology, although all of them share some common binding site for ions important in stabilizing the enzyme
the enzyme is stable up to 45°C in 50 mM Tris/HCl, pH 7.5, containing 0.1 M NaCl and 1 mM CaCl2 for 1 h. Incubation at 45°C inactivates the enzyme completely within 5 min at either condition of low NaCl concentration (less than 10 mM) or presence of 10 mM EDTA
synthetic gene CGIOP, locus MF459059 in GenBank, codon-optimized gene encoding the iota-carrageenase without a signal peptide, cloned from gene cgiA of Microbulbifer thermotolerans strain JAMB-A94, construction of the integrative vector pBCGA, recombinant expression of extracellular His-tagged enzyme in Brevibacillus choshinensis strain HPD31-SP3, real-time PCR expression analysis, copy numbers of the CGIOP gene in different lines are approximately 5-6, respectively
Hyper-production and characterization of the iota-carrageenase useful for iota-carrageenan oligosaccharide production from a deep-sea bacterium, Microbulbifer thermotolerans JAMB-A94T, and insight into the unusual catalytic mechanism
Efficient production of a recombinant iota-carrageenase in Brevibacillus choshinensis using a new integrative vector for the preparation of iota-carrageenan oligosaccharides