Glycoside Hydrolase Family 5

• Author: ^^^Gideon Davies^^^
• Responsible Curator: ^^^Gideon Davies^^^

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Glycoside Hydrolase Family GH5
Clan	GH-x
Mechanism	retaining/inverting
Active site residues	known/not known
CAZy DB link
http://www.cazy.org/fam/GH5.html

Substrate specificities

GH5 is one of the largest of all CAZy hydrolase families with almost 2000 distinct sequence entries and with (23-Sept 2009) 36 different proteins having a 3-D structure deposited. A variety of specificties are annotated to this family notably endoglucanase (cellulase) and endomannanase as well as exoglucanases, exomannanases and b-glucodsidase and b-mannosidase. Other activities include 1,6 galactanase, 1,3 mannanase, 1,4 xylanase as well as high specificity xyloglucanases. The Rhodococcal endoglycoceramidase II (EGC) in this family has found application in the chemoenzymatic synthesis of ceramide derivatives.

Family GH5 enzymes are found widely distributed across Archae, bacteria and eukaryotes, notably fungi and plants. There are no known human enzymes in GH5.

This is an example of how to make references to a journal article [1]. (See the References section below). Multiple references can go in the same place like this [1, 2]. You can even cite books using just the ISBN [3]. References that are not in PubMed can be typed in by hand [4].

Kinetics and Mechanism

Family GH5 enzymes are retaining enzymes, as first shown by NMR [XXX] and follow a classical Koshland double-displacement mechanism.

Catalytic Residues

Content is to be added.

Three-dimensional structures

Three-dimensional structures are available for a very large number of Family GH5 enzymes, the first solved being that of the Clostridium thermocellum endoglucanase CelC [11]. As members of Clan GH-A they have a classical (α/β)8 TIM barrel fold with the two key active site glutamic acids being approximately 200 residues apart in sequence and located at the C-terminal ends of β-strands 4 (acid/base) and 7 (nucleophile) [12]. With so many 3D structures in this family, covering many specificities it is clearly hard to pick out notable structural papers. The Bacillus agaradhaerens Cel5A has been extensively studied, notably in the trapping of enzymatic snapshots along the reaction coordinate *** but also as a testbed for glycosidase inhibitor design as crystals often diffract to atomic resolution (for example ***).

Family Firsts

First sterochemistry determination

Cite some reference here, with a short (1-2 senetence) explanation [1].

First catalytic nucleophile identification

Cite some reference here, with a short (1-2 senetence) explanation [4].

First general acid/base residue identification

Cite some reference here, with a short (1-2 senetence) explanation [2].

First 3-D structure

The first 3D structures in family GH5 was an endoglucanase (cellulase)from Clostridium thermocellum reported by the Alzari in 1995 (in a paper which also reported a family GH10 xylanase structure and the similarities between them) [3]. Subsequently, Ducros and colleagues reported the Clostridium cellulolyticum Cel5A also in 1995 [5]..

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 |
2. He S and Withers SG. (1997). Assignment of sweet almond beta-glucosidase as a family 1 glycosidase and identification of its active site nucleophile. J Biol Chem. 1997;272(40):24864-7. DOI:10.1074/jbc.272.40.24864 |
3. Robert V. Stick and Spencer J. Williams. (2009) Carbohydrates. Elsevier Science.

4. Sinnott, M.L. (1990) Catalytic mechanisms of enzymic glycosyl transfer. Chem. Rev. 90, 1171-1202. DOI: 10.1021/cr00105a006

[[Category:Glycoside Hydrolase Families|GHnnn]]