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Difference between revisions of "Glycoside Hydrolase Family 32"
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== Family Firsts == | == Family Firsts == | ||
;First sterochemistry determination: Cite some reference here, with a ''short'' explanation <cite>1</cite>. | ;First sterochemistry determination: Cite some reference here, with a ''short'' explanation <cite>1</cite>. | ||
| − | ;First catalytic nucleophile identification: | + | ;First [[catalytic nucleophile]] identification: |
| − | ;First general acid/base residue identification: | + | ;First [[general acid/base]] residue identification: |
;First 3-D structure: | ;First 3-D structure: | ||
Revision as of 20:26, 31 August 2009
| Glycoside Hydrolase Family GH32 | |
| Clan | GH-J |
| Mechanism | retaining |
| Active site residues | known |
| CAZy DB link | |
| http://www.cazy.org/fam/GH32.html | |
Substrate specificities
Glycoside hydrolase family GH32 contains one of the earliest described enzyme activities, namely that of 'inverting' sucrose, from which is derived the name of 'invertase' (EC 3.2.1.26), discovered in the second half of the 19th century [1]. Besides the 'historical' invertases, this family also contains enzymes that hydrolyze fructose containing polysaccharides such as inulinases (EC 3.2.1.7) and exo-inulinases (EC 3.2.1.80), levanases (EC 3.2.1.65) and β-2,6-fructan 6-levanbiohydrolases(EC 3.2.1.64), fructan β-(2,1)-fructosidase/1-exohydrolase (EC 3.2.1.153) or fructan β-(2,6)-fructosidase/6-exohydrolases (EC 3.2.1.154), as well as enzymes displaying transglycosylating activites such as sucrose:sucrose 1-fructosyltransferases (EC 2.4.1.99), fructan:fructan 1-fructosyltransferase (EC 2.4.1.100), sucrose:fructan 6-fructosyltransferase (EC 2.4.1.10), fructan:fructan 6G-fructosyltransferase (EC 2.4.1.243) and levan fructosyltransferases (EC 2.4.1.-).
Kinetics and Mechanism
Family 32 enzymes are retaining enzymes, as first shown by Koshland and Stein by performing the reaction in 18O-labeled water and determining the 18O content of the products [2]. The transfructosylation activity (a type of transglycosylation activity) observed for invertase in this reaction indicated that the enzyme operates with a molecular mechanism leading to overall retention of the anomeric configuration [2].
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
-
O'Sullivan, C., and Tompson, F. W. (1890) J. Chem. Soc. 57, 854-870
- KOSHLAND DE Jr and STEIN SS. (1954). Correlation of bond breaking with enzyme specificity; cleavage point of invertase. J Biol Chem. 1954;208(1):139-48. | Google Books | Open Library