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Difference between revisions of "Glycoside Hydrolase Family 26"
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This family consists primarily of endo-beta1,4-mannanases, although a recent exo-acting beta- mannanase has been described. The family also contains enzymes that display beta-1,3:1,4-glucanase <cite>#1</cite> and beta-1,3 xylanase activities. | This family consists primarily of endo-beta1,4-mannanases, although a recent exo-acting beta- mannanase has been described. The family also contains enzymes that display beta-1,3:1,4-glucanase <cite>#1</cite> and beta-1,3 xylanase activities. | ||
| − | == Kinetics and Mechanism == | + | == Kinetics and Mechanism ==\ Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 |
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| + | Family GH10 enzymes are “retainers”, as shown by NMR and follow a classical Koshland double-displacement mechanism. Pre-steady state kinetics using activated substrates revealed the two phases of the reaction; the rapid initial glycosylation step (only with good leaving groups) followed by the slower deglycosylation. It should be noted that the use of substrates with a good leaving group result in a very low apparent KM, particularly with the acid-base mutant. This does not reflect tight affinity but simply that the glycosylation step (k2) is much quicker than the deglycosylation step (k3) {Bolam, 1996 #7}. | ||
== Catalytic Residues == | == Catalytic Residues == | ||
Revision as of 10:38, 29 June 2009
Substrate specificities
This family consists primarily of endo-beta1,4-mannanases, although a recent exo-acting beta- mannanase has been described. The family also contains enzymes that display beta-1,3:1,4-glucanase [1] and beta-1,3 xylanase activities.
== Kinetics and Mechanism ==\ Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4
Family GH10 enzymes are “retainers”, as shown by NMR and follow a classical Koshland double-displacement mechanism. Pre-steady state kinetics using activated substrates revealed the two phases of the reaction; the rapid initial glycosylation step (only with good leaving groups) followed by the slower deglycosylation. It should be noted that the use of substrates with a good leaving group result in a very low apparent KM, particularly with the acid-base mutant. This does not reflect tight affinity but simply that the glycosylation step (k2) is much quicker than the deglycosylation step (k3) {Bolam, 1996 #7}.
Catalytic Residues
Three-dimensional structures
Family Firsts
- First sterochemistry determination
- Cite some reference here, with a short explanation [1].
- First catalytic nucleophile identification
- First general acid/base residue identification
- First 3-D structure
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 |
- Araki T, Hashikawa S, and Morishita T. (2000). Cloning, sequencing, and expression in Escherichia coli of the new gene encoding beta-1,3-xylanase from a marine bacterium, Vibrio sp. strain XY-214. Appl Environ Microbiol. 2000;66(4):1741-3. DOI:10.1128/AEM.66.4.1741-1743.2000 |