CAZypedia needs your help! We have many unassigned GH, PL, CE, AA, GT, and CBM pages in need of Authors and Responsible Curators.
Scientists at all career stages, including students, are welcome to contribute to CAZypedia. Read more here, and in the 10th anniversary article in Glycobiology.
New to the CAZy classification? Read this first.
Consider attending the 15th Carbohydrate Bioengineering Meeting in Ghent, 5-8 May 2024.

Glycoside Hydrolase Family 174

From CAZypedia
Jump to navigation Jump to search
Approve icon-50px.png

This page has been approved by the Responsible Curator as essentially complete. CAZypedia is a living document, so further improvement of this page is still possible. If you would like to suggest an addition or correction, please contact the page's Responsible Curator directly by e-mail.

Glycoside Hydrolase Family GH174
Clan GH-x
Mechanism retaining/inverting
Active site residues known/not known
CAZy DB link

Substrate specificities

Members of glycoside hydrolase family 174 have been shown to exhibit α-1,3-L-fucanase activity. The first member of this family, Fun174A from a marine bacterium Wenyingzhuangia aestuarii OF219, 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 processive endo-acting manner.[1] Meanwhile, three homologs of Fun174A from Rubritalea marina, Spartobacteria bacterium and Wenyingzhuangia fucanilytica, display activities toward sulfated fucan from Isostichopus badionotus.[1] All 92 members (up to May,2023) of GH174 are bacterial enzymes.

Figure 1. The phylogenetic tree of GH174 homologs. Sequences comfirmed to exhibit α-1,3-L-fucanase activity were in red.

Kinetics and Mechanism

The catalytic mechanism of GH174 has not been identified. As mentioned in the report, Fun174A showed no transglycosylating activity in the tested acceptor substrates, such as glycerin, methanol, L-fucose, D-glucose, D-galactose, D-fructose, D-mannose, D-glucosamine and N-acetyl- D-glucosamine.[1]

Catalytic Residues

Multiple sequence alignments of GH174 homologs showed that D119, E120 and E218 in Fun174A were highly conserved in all sequences. Three single-site mutants D119E, E120A and E218Q were established, expressed and identified in the report. Mutant D119E, E120A and E218Q resulted in 100.0%, 85.7% and 88.3% loss of activity on sulfated fucan from Isostichopus badionotus respectively. It indicated that D119, E120 and E218 were critical for the functioning of Fun174A.[1]

Figure 2. Multiple sequence alignments of residues in GH174 homologs. The highly conserved acidic amino acids in all sequences were indicated with black triangles.

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.


  1. Liu G, Shen J, Chang Y, Mei X, Chen G, Zhang Y, and Xue C. (2023). Characterization of an endo-1,3-fucanase from marine bacterium Wenyingzhuangia aestuarii: The first member of a novel glycoside hydrolase family GH174. Carbohydr Polym. 2023;306:120591. DOI:10.1016/j.carbpol.2023.120591 | PubMed ID:36746582 [Liu2023]