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Difference between revisions of "Glycoside Hydrolase Family 49"
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== Substrate specificities == | == Substrate specificities == | ||
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[[Glycoside hydrolase]]s of family 49 cleave α-1,6-linkages or α-1,4-linkages of polysaccharides containing α-1,6-linkages, dextran and pullulan. The major activities reported for this family of glycoside hydrolases are dextranase (EC [{{EClink}}3.2.1.11 3.2.1.11]). Dextran 1,6-α-isomaltotriosidase (EC [{{EClink}}3.2.1.95 3.2.1.95]) and isopullulanase (EC [{{EClink}}3.2.1.57 3.2.1.57]) activities have also been described. | [[Glycoside hydrolase]]s of family 49 cleave α-1,6-linkages or α-1,4-linkages of polysaccharides containing α-1,6-linkages, dextran and pullulan. The major activities reported for this family of glycoside hydrolases are dextranase (EC [{{EClink}}3.2.1.11 3.2.1.11]). Dextran 1,6-α-isomaltotriosidase (EC [{{EClink}}3.2.1.95 3.2.1.95]) and isopullulanase (EC [{{EClink}}3.2.1.57 3.2.1.57]) activities have also been described. | ||
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== Catalytic Residues == | == Catalytic Residues == | ||
| − | + | Three Asp residues (Asp376, Asp395, and Asp396 in Dex49A) are conserved in the catalytic centre of members of Clan GH-N, GH49 and GH28 enzymes, and all three of the Asp mutants of a GH49 enzyme, isopullulanase, lost their activities. The general acid was first identified in Dex49A from ''Penicillium minioluteum'' as Asp395 following the three-dimensional structure determination. To date, it is unclear whether either of the Asp residues (Asp376 and Asp396 in Dex49A) acts as a base in the reaction of both GH49 and GH28 enzymes. | |
== Three-dimensional structures == | == Three-dimensional structures == | ||
| − | + | GH49 enzymes display a two domain structure. The N-terminal domain is a β-sandwich and the C-terminal domain adopts a right-handed parallel β-helix. | |
Revision as of 03:51, 17 May 2010
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: ^^^Takashi Tonozuka^^^
- Responsible Curator: ^^^Takashi Tonozuka^^^
| Glycoside Hydrolase Family GHnn | |
| Clan | GH-N |
| Mechanism | inverting |
| Active site residues | known |
| CAZy DB link | |
| http://www.cazy.org/fam/GHnn.html | |
Substrate specificities
Glycoside hydrolases of family 49 cleave α-1,6-linkages or α-1,4-linkages of polysaccharides containing α-1,6-linkages, dextran and pullulan. The major activities reported for this family of glycoside hydrolases are dextranase (EC 3.2.1.11). Dextran 1,6-α-isomaltotriosidase (EC 3.2.1.95) and isopullulanase (EC 3.2.1.57) activities have also been described.
Kinetics and Mechanism
Family GH49 α-glycosidases are inverting enzymes, as first shown by NMR on a dextranase Dex49A from Penicillium minioluteum.
Catalytic Residues
Three Asp residues (Asp376, Asp395, and Asp396 in Dex49A) are conserved in the catalytic centre of members of Clan GH-N, GH49 and GH28 enzymes, and all three of the Asp mutants of a GH49 enzyme, isopullulanase, lost their activities. The general acid was first identified in Dex49A from Penicillium minioluteum as Asp395 following the three-dimensional structure determination. To date, it is unclear whether either of the Asp residues (Asp376 and Asp396 in Dex49A) acts as a base in the reaction of both GH49 and GH28 enzymes.
Three-dimensional structures
GH49 enzymes display a two domain structure. The N-terminal domain is a β-sandwich and the C-terminal domain adopts a right-handed parallel β-helix.
Family Firsts
- First stereochemistry determination
- Cite some reference here, with a short (1-2 sentence) explanation [1].
- First catalytic nucleophile identification
- Cite some reference here, with a short (1-2 sentence) explanation [2].
- First general acid/base residue identification
- Cite some reference here, with a short (1-2 sentence) explanation [3].
- First 3-D structure
- Cite some reference here, with a short (1-2 sentence) explanation [4].
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 |