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Glycoside Hydrolase Family 45
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- Author: ^^^Gideon Davies^^^
- Responsible Curator: ^^^Gideon Davies^^^
| Glycoside Hydrolase Family GH45 | |
| Clan | none |
| Mechanism | inverting |
| Active site residues | known (but see discussion) |
| CAZy DB link | |
| http://www.cazy.org/fam/GH45.html | |
Substrate specificities
Endoglucanases (EC 3.2.1.4). Mainly the hydrolysis of soluble beta 1,4 glucans.
Kinetics and Mechanism
The enzymes act with inversion of anomeric configuration to generate the alpha-D glucoside as product. Based upon the structure of the Humicola insolens endoglucanase V (now known as Cel45) it was concluded that Asp121 acted as the catalytic acid (implied by its hydrogen bonding to the glycosidic oxygen) and that the most likely catalytic base would be Asp10, appropriately positioned "below" the sugar plane. As with many inverting enzymes the base assignment is less secure than that of the acid.
Catalytic Residues
Content is to be added here.
Three-dimensional structures
Content is to be added here.
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 [2].
- First general acid/base residue identification
- Cite some reference here, with a short (1-2 senetence) explanation [3].
- First 3-D structure
- The Humicola insolens EGV (now Cel45) by the Davies group [4].
References
-
Sinnott, M.L. (1990) Catalytic mechanisms of enzymic glycosyl transfer. Chem. Rev. 90, 1171-1202. DOI: 10.1021/cr00105a006
- 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 |
- Rouvinen J, Bergfors T, Teeri T, Knowles JK, and Jones TA. (1990). Three-dimensional structure of cellobiohydrolase II from Trichoderma reesei. Science. 1990;249(4967):380-6. DOI:10.1126/science.2377893 |
- Robert V. Stick and Spencer J. Williams. (2009) Carbohydrates. Elsevier Science.
[[Category:Glycoside Hydrolase Families|GHnnn]]