Glycoside Hydrolase Family 67

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• Author: Harry Gilbert
• Responsible Curator: Harry Gilbert

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Glycoside Hydrolase Family GHnn
Clan	GH-x
Mechanism	retaining/inverting
Active site residues	known/not known
CAZy DB link
http://www.cazy.org/fam/GHnn.html

Substrate specificities

GH67 contains enzymes that display alpha-glucuronidase activity. The enzymes target the glucuronic acid appended to the C2-OH of the xylose at the non-reducing end of xylooligosaccharides. The length of the oligosacchride do not influence catalytic rate indicating that the enzyme only interacts with the uronic acid and the linked xylose. These enzymes do not remove glucuronic acid from internal regions of xylan (cite)#1#2(/cite). The enzymes are generally intracellular or membrane associated (cite)#3#4(/cite)suggesting that they play a terminal role in uncapping decorated xyloooligosacchrides, making these molecules available to beta-xylosidases produced by the host.

Kinetics and Mechanism

Alpha-glucuronidases hydrolyse their target glycoside bond through a single displacement acid-basee assisted mechanism, and thus the released glucuronic acid is in a beta conformation.

Family Firsts

First sterochemistry determination

Cite some reference here, with a short explanation [1].

First catalytic nucleophile identification

First general acid/base residue identification

First 3-D structure

References

1. Comfort DA, Bobrov KS, Ivanen DR, Shabalin KA, Harris JM, Kulminskaya AA, Brumer H, and Kelly RM. (2007). Biochemical analysis of Thermotoga maritima GH36 alpha-galactosidase (TmGalA) confirms the mechanistic commonality of clan GH-D glycoside hydrolases. Biochemistry. 2007;46(11):3319-30. DOI:10.1021/bi061521n |