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Difference between revisions of "Glycoside Hydrolase Family 140"
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== Kinetics and Mechanism == | == Kinetics and Mechanism == | ||
| − | GH140 likely uses a, retaining, double displacement mechanism. This is strongly supported by methanolysis experiments using the trisaccharide L-rhamnose-β1,3-D-apiose-α1,2-D-galacturonic acid-O-methyl in the presence of 10% methanol. This experiment generates the product L-rhamnose-β1,3-D-apiose- | + | GH140 likely uses a, retaining, double displacement mechanism. This is strongly supported by methanolysis experiments using the trisaccharide L-rhamnose-β1,3-D-apiose-α1,2-D-galacturonic acid-O-methyl in the presence of 10% methanol. This experiment generates the product L-rhamnose-β1,3-D-apiose-O-methyl which is only possible via a retaining mechanism. |
== Catalytic Residues == | == Catalytic Residues == | ||
Revision as of 13:23, 15 December 2018
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: ^^^Alan Cartmell^^^
- Responsible Curator: ^^^Harry Gilbert^^^
| Glycoside Hydrolase Family GH140 | |
| Clan | GH-x |
| Mechanism | retaining |
| Active site residues | known |
| CAZy DB link | |
| https://www.cazy.org/GH140.html | |
Substrate specificities
Thus far only one member of the family has been characterised, BT1012 from bacteroides thetaiotaomicron. BT1012 displays apiosidase activity targeting apiose in the complex glycan rhamnogalacturonan ii (RGII). The apiose is found at the base of Chains A and B in RGII and linked α1,2 to the galacturonic acid backbone. Cleavage of the backbone must occur for BT1012 to then act.
Kinetics and Mechanism
GH140 likely uses a, retaining, double displacement mechanism. This is strongly supported by methanolysis experiments using the trisaccharide L-rhamnose-β1,3-D-apiose-α1,2-D-galacturonic acid-O-methyl in the presence of 10% methanol. This experiment generates the product L-rhamnose-β1,3-D-apiose-O-methyl which is only possible via a retaining mechanism.
Catalytic Residues
The catalytic residues are an aspartate and glutamate located on beta strands 4 and 7, respectively.
Three-dimensional structures
GH140 adopts a (β/α)8 , TIM barrel, where a central barrel of eight β strands are encircled by eight α helices. BT1012, the only GH140 strcuture available, also has a Ig like domain that stacks against the TIM barrel likely providing structural stability, similar to the role of Ig like domains in GH43 enzymes.
Family Firsts
- First stereochemistry determination
- Content is to be added here.
- First catalytic nucleophile identification
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- First general acid/base residue identification
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- First 3-D structure
- Content is to be added here.
References
- Cantarel BL, Coutinho PM, Rancurel C, Bernard T, Lombard V, and Henrissat B. (2009). The Carbohydrate-Active EnZymes database (CAZy): an expert resource for Glycogenomics. Nucleic Acids Res. 2009;37(Database issue):D233-8. DOI:10.1093/nar/gkn663 |
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Davies, G.J. and Sinnott, M.L. (2008) Sorting the diverse: the sequence-based classifications of carbohydrate-active enzymes. The Biochemist, vol. 30, no. 4., pp. 26-32. Download PDF version.