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Glycoside Hydrolase Family 139

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Glycoside Hydrolase Family GH139
Clan none
Mechanism unknown
Active site residues not known
CAZy DB link

Substrate specificities

Glycoside hydrolases of family 139 family display α-2-O-methyl-L-fucosidase activity. They are exclusively bacterial in origin. The enzyme BT0984 from Bacteroides thetaiotaomicron is the only member of this family that has been characterized. This exo-acting enzyme targets the 2-O-methyl-L-fucose-α-1,2-D-Galp linkage in chain B of the complex pectin rhamnogalacturonan-II [1].

Kinetics and Mechanism

The stereochemistry of the reaction catalyzed by GH139 members has not yet been reported.

Catalytic Residues

Not known.

Three-dimensional structures

No three-dimensional structure has been solved for this family.

Family Firsts

First stereochemistry determination
First catalytic nucleophile identification
First general acid/base residue identification
First 3-D structure


  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 | PubMed ID:28329766 [Ndeh2017]