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Glycoside Hydrolase Family 57
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- Author: ^^^Stefan Janecek^^^
- Responsible Curator: ^^^Stefan Janecek^^^
| Glycoside Hydrolase Family GH57 | |
| Clan | not assigned yet |
| Mechanism | retaining |
| Active site residues | known/not known |
| CAZy DB link | |
| http://www.cazy.org/fam/GH57.html | |
Substrate specificities
Normal 0 21 false false false SK X-NONE X-NONE MicrosoftInternetExplorer4 The family GH57 was established in 1996 (Henrissat & Bairoch 1996) based on the existence of the sequences of two “α-amylases” that were dissimilar to typical family GH13 α-amylases (MacGregor et al. 2001). The two were the heat-stable eubacterial amylase from Dictyoglomus thermophilum known from 1988 (Fukusumi et al. 1988) and the extremely thermostable archaeal amylase from Pyrococcus furiosus determined in 1993 (Laderman et al. 1993a).
Normal 0 21 false false false SK X-NONE X-NONE MicrosoftInternetExplorer4 The family has expanded mainly due to running genome sequencing projects. Nowadays it contains more than 400 members; all originating from prokaryotes (http://www.cazy.org/fam/GH57.html). With regard to the enzyme specificities, the family GH57 covers the α-amylase (EC 3.2.1.1), α-galactosidase (EC 3.2.1.22), amylopullulanase (EC 3.2.1.1/41), branching enzyme (EC 2.4.1.18) and 4-α-glucanotransferase (EC 2.4.1.25). It is worth mentioning that the two constituent members, i.e. the “α-amylases” from D. thermophilum and P. furiosus are rather the 4-α-glucanotransferases since the former was later proven to have the transglycosylating activity (Nakajima et al. 2004), whereas the latter was shown already in 1993 to exhibit the 4-α-glucanotransferase activity (Laderman et al., 1993b). And it is also of interest that the real enzymes form only about 5% of the family members. The vast majority of the GH57 are hypothetical proteins.
Kinetics and Mechanism
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Catalytic Residues
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Three-dimensional structures
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Family Firsts
- First sterochemistry determination
- Cite some reference here, with a short (1-2 sentence) explanation.
- First catalytic nucleophile identification
- Cite some reference here, with a short (1-2 sentence) explanation.
- First general acid/base residue identification
- Cite some reference here, with a short (1-2 sentence) explanation.
- First 3-D structure
- The first 3-D structure of a GH57 member was that of the 4-alpha-glucanotransferase from Thermococcus litoralis [1].