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Difference between revisions of "Glycoside Hydrolase Family 92"
| Line 32: | Line 32: | ||
== Kinetics and Mechanism == | == Kinetics and Mechanism == | ||
| + | 1H-NMR studies on three GH92s that displayed alpha1,2-, alpha1,3- and alpha1,4-mannosidase activities all generated beta-mannose indicating that these enzymes catalyse glycosidic bond hydrolysis through a single displacement mechanism leading to inversion of anomeric configuration <cite>Zhu et al </cite>. | ||
== Catalytic Residues == | == Catalytic Residues == | ||
Revision as of 09:25, 26 October 2009
This page is currently under construction. This means that the Responsible Curator has deemed that the page's content is not quite up to CAZypedia's standards for full public consumption. All information should be considered to be under revision and may be subject to major changes.
- Author: ^^^Harry Gilbert^^^
- Responsible Curator: ^^^Harry Gilbert^^^
| 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
GH92 enzymes are exo-acting alpha-mannosidases. The first reported enzyme activity from this family was an alpha1,2-mannosidase from Microbacterium sp. M-90. [1] Recently the characterization of 22 GH92 enzymes from Bacteroides thetaiotaomicron confirmed an exo-mode of action but alpha1,2-mannosidase, alpha1,3-mannosidase, alpha1,4-mannosidase and alpha1,6-mannosidase activities were detected [2] [3, 4, 5].
Kinetics and Mechanism
1H-NMR studies on three GH92s that displayed alpha1,2-, alpha1,3- and alpha1,4-mannosidase activities all generated beta-mannose indicating that these enzymes catalyse glycosidic bond hydrolysis through a single displacement mechanism leading to inversion of anomeric configuration [3, 4, 5].
Catalytic Residues
Content is to be added here. Based on 3D structural data on the alpha1,2-mannosidase Bt3990 Glu533 is the predicted catalytic acid. This view is supported by a mutant of this residue, which is essentially inactive, and its conservation throughout the GH92 family.
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 [6].
- First catalytic nucleophile identification
- Cite some reference here, with a short (1-2 sentence) explanation [7].
- First general acid/base residue identification
- Cite some reference here, with a short (1-2 sentence) explanation [8].
- First 3-D structure
- Cite some reference here, with a short (1-2 sentence) explanation [9].
References
- 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 |
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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 |
- Robert V. Stick and Spencer J. Williams. (2009) Carbohydrates. Elsevier Science.