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Glycoside Hydrolase Family 12
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- Author: ^^^Mats Sandgren^^^
- Responsible Curator: ^^^Mats Sandgren^^^
| Glycoside Hydrolase Family GHnn | |
| Clan | GH-C |
| Mechanism | retaining |
| Active site residues | known |
| CAZy DB link | |
| http://www.cazy.org/fam/GH12.html | |
Substrate specificities
The substrate specificities found among the glycoside hydrolases of family 12 are: endo-β-1,4-glucanase (EC 3.2.1.4), xyloglucan hydrolase (EC 3.2.1.151), endo-β-1,3-1,4-glucanase (EC 3.2.1.73), and xyloglucan endo-transglycosylase (EC 2.4.1.207),.
Kinetics and Mechanism
GH Family 12 enzymes are retaining enzymes, as first shown by NMR studdies [1] on endoglucanase 3 from Humicola insolens, and follow a classical Koshland double-displacement mechanism. No detailed studies involving both steady state and pre-steady state kinetic have yet been reported for this family.
Catalytic Residues
The catalytic nucleophile of GH family 12 enzymes was initialy predicted by sequence homology to the xylanase members of GH family 11, a glycoside hydrolase family where the catalytic nucleophile was first identified in the Bacillus circulans endo-xylanase through trapping of the 2-deoxy-2-fluoroxylobiosyl-enzyme intermediate and subsequent peptide mapping via LC-MS/MS technologies [2]. GH family 11 and 12 form together GH clan C of related GH families. The predicted catalytic nucleophile was subsequentialy confirmed through
Three-dimensional structures
Content is to be added here.
Family Firsts
- First sterochemistry determination
- Cite some reference here, with a short (1-2 sentence) explanation [3].
- First catalytic nucleophile identification
- Cite some reference here, with a short (1-2 sentence) explanation [4].
- First general acid/base residue identification
- Cite some reference here, with a short (1-2 sentence) explanation [5].
- First 3-D structure
- Cite some reference here, with a short (1-2 sentence) explanation [6].
References
- Schou C, Rasmussen G, Kaltoft MB, Henrissat B, and Schülein M. (1993). Stereochemistry, specificity and kinetics of the hydrolysis of reduced cellodextrins by nine cellulases. Eur J Biochem. 1993;217(3):947-53. DOI:10.1111/j.1432-1033.1993.tb18325.x |
- Miao S, Ziser L, Aebersold R, and Withers SG. (1994). Identification of glutamic acid 78 as the active site nucleophile in Bacillus subtilis xylanase using electrospray tandem mass spectrometry. Biochemistry. 1994;33(23):7027-32. DOI:10.1021/bi00189a002 |