Glycoside Hydrolase Family 138

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• Author: ^^^Didier Ndeh^^^
• Responsible Curator: ^^^Harry Gilbert^^^

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Glycoside Hydrolase Family GH138
Clan	none
Mechanism	unknown
Active site residues	unknown
CAZy DB link
https://www.cazy.org/GH138.html

Substrate specificities

Glycoside hydrolases of family 138 (GH138) exhibit α-D-galacturonidase activity. This is based on data from the characterisation of the founding member of the family BT0997 encoded by the prominent human gut bacterium B. thetaiotaomicron [1]. BT0997 hydrolyses a derivative fragment (GalAα1-2(GalAβ1-3)(2MeXylα1-3Fucα1-4)Rhaα1-3Api) of Chain A from the pectic polysaccharide Rhamnogalacturonan II, producing D-galacturonic acid and the resulting fragment GalAβ1-3(2MeXylα1-3Fucα1-4)Rhaα1-3Api [1]. To date, over 33 members of this family have been identified in gut and environmental bacteria and a majority of the encoding microbes (over 80%) belong to the Bacteroidetes phylum [2, 3]. This phylum is highly represented in human gut microbial populations [4].

Kinetics and Mechanism

The kinetic mechanism for this family has not been reported

Catalytic Residues

The catalytic residues for this family have not yet been identified.

Three-dimensional structures

No 3D structure for a member of this family has been currently reported

Family Firsts

First stereochemistry determination

Currently unknown.

First catalytic nucleophile identification

Currently unknown.

First general acid/base residue identification

Currently unknown.

First 3-D structure

Currently unknown.

References

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1. Ndeh D, Rogowski A, Cartmell A, Luis AS, Baslé A, Gray J, Venditto I, Briggs J, Zhang X, Labourel A, Terrapon N, Buffetto F, Nepogodiev S, Xiao Y, Field RA, Zhu Y, O'Neil MA, Urbanowicz BR, York WS, Davies GJ, Abbott DW, Ralet MC, Martens EC, Henrissat B, and Gilbert HJ. (2017). Complex pectin metabolism by gut bacteria reveals novel catalytic functions. Nature. 2017;544(7648):65-70. DOI:10.1038/nature21725 |