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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5. Davies, G.J. and Sinnott, M.L. (2008) Sorting the diverse: the sequence-based classifications of carbohydrate-active enzymes. The Biochemist, vol. 30, no. 4., pp. 26-32. Download PDF version.