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Glycoside Hydrolase Family 168
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| Glycoside Hydrolase Family GH168 | |
| Clan | GH-x |
| Mechanism | retaining/inverting |
| Active site residues | known/not known |
| CAZy DB link | |
| http://www.cazy.org/GH168.html | |
Substrate specificities
Members of glycoside hydrolase family 168 have been shown to exhibit α-1,3-L-fucanase activity. The first member of this family, Fun168A from a marine bacterium Wenyingzhuangia funcanilytica CZ1127T, specifically hydrolyze the α-1,3- L-fucoside bonds between 2-O-sulfated and non-sulfated fucose residues in the sulfated fucan from sea cucumber Isostichopus badionotus in a random endo-acting manner [1]. Meanwhile, five homologues of Fun168A display activities toward sulfated fucan from Isostichopus badionotus, namely WP_081987558.1, WP_068826447.1, WP_068826442.1, OHE80969.1 and WP_083194720.1.
Kinetics and Mechanism
As mentioned in the report, Fun168A exhibited transglycosylating activity with glycerin, methanol, and L-fucose as acceptors. The transglycosylating activity of Fun168A implied its retaining mechanism in catalysis.
Catalytic Residues
Multiple sequence alignments of GH168 homologues showed that D206 and E264 in Fun168A were strictly conserved in all sequences. Two single-site mutants D206E and E264Q were established, expressed and identified in the report. These two mutants were all inactive on Ib-FUC, indicating that D206 and E264 were critical for the activity of Fun168A.
Three-dimensional structures
No three-dimensional structure has been solved in this glycoside hydrolase family at present.
Family Firsts
- First stereochemistry determination
- Not yet identified.
- First catalytic nucleophile identification
- Not yet identified.
- First general acid/base residue identification
- Not yet identified.
- First 3-D structure
- Not yet identified.