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Glycoside Hydrolase Family 168
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Glycoside Hydrolase Family GH168 | |
Clan | GH-x |
Mechanism | retaining |
Active site residues | not known |
CAZy DB link | |
http://www.cazy.org/GH168.html |
Substrate specificities
Members of GH168 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 hydrolyzes 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. Meanwhile, five homologues of Fun168A display activities toward sulfated fucan from Isostichopus badionotus [1].
Kinetics and Mechanism
W. funcanilytica Fun168A exhibited transglycosylating activity with glycerin, methanol, and L-fucose as acceptors. This transglycosylating activity implied a retaining mechanism of catalysis [1].
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 of W. funcanilytica Fun168A, D206E and E264Q, were inactive on Ib-FUC, indicating that D206 and E264 were critical for activity [1].
Three-dimensional structures
No three-dimensional structure has been solved in this 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.