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Difference between revisions of "Glycoside Hydrolase Family 75"
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| − | * [[Author]]: | + | * [[Author]]: ^^^Ryszard Brzezinski^^^ |
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== Substrate specificities == | == Substrate specificities == | ||
| − | Glycoside hydrolases of family 75 include both eukaryotic (essentially fungal) and prokaryotic proteins. They have so far been characterized only from filamentous fungi. They are | + | Glycoside hydrolases of family 75 include both eukaryotic (essentially fungal) and prokaryotic proteins. They have so far been characterized only from filamentous fungi. They are beta-1,4-chitosanases with endo-splitting activity <cite>Shimosaka1993 Cheng2000</cite>. The analysis of the final product of hydrolysis of partially ''N''-deacetylated chitosan by the GH75 chitosanase from ''Aspergillus fumigatus'' suggests that this enzyme cleaves preferentially GlcN-GlcN and GlcNAc-GlcN links in the polysaccharide chain <cite>Cheng2006</cite>. |
== Kinetics and Mechanism == | == Kinetics and Mechanism == | ||
Revision as of 12:36, 3 June 2011
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: ^^^Ryszard Brzezinski^^^
- Responsible Curator: ^^^Ryszard Brzezinski^^^
| Glycoside Hydrolase Family GH75 | |
| Clan | Not assigned |
| Mechanism | Inverting |
| Active site residues | Inferred |
| CAZy DB link | |
| https://www.cazy.org/GH75.html | |
Substrate specificities
Glycoside hydrolases of family 75 include both eukaryotic (essentially fungal) and prokaryotic proteins. They have so far been characterized only from filamentous fungi. They are beta-1,4-chitosanases with endo-splitting activity [1, 2]. The analysis of the final product of hydrolysis of partially N-deacetylated chitosan by the GH75 chitosanase from Aspergillus fumigatus suggests that this enzyme cleaves preferentially GlcN-GlcN and GlcNAc-GlcN links in the polysaccharide chain [3].
Kinetics and Mechanism
Family GH46 enzymes are classified as inverting enzymes. This has been shown by 1H NMR for the enzyme from Aspergillus fumigatus using chitosan as substrate [3].
Catalytic Residues
A site-directed mutagenesis study performed on the enzyme from Fusarium solani (expressed as a recombinant protein in Saccharomyces cerevisiae) showed that Asp175 and Glu188 are essential for catalysis [4]. This was confirmed by a study on the chitosanase from Aspergillus fumigatus (expressed as a recombinant protein in Escherichia coli) showing that the corresponding residues Asp160 and Glu169 are essential for catalysis [3]. Both residues are strictly conserved among eukaryotic and prokaryotic GH75 family members.
Three-dimensional structures
No three-dimensional structure has been solved for this family.
Family Firsts
- First primary structure determination
- Chitosanase from Fusarium solani f. sp. phaseoli [5].
- First stereochemistry determination
- Chitosanase from Aspergillus fumigatus [3].
- First catalytic nucleophile identification
- Not yet identified.
- First general acid/base residue identification
- Not yet identified.
- First 3-D structure
- Not yet determined.
References
-
Shimosaka M, Nogawa M, Ohno Y, and Okazaki M. Chitosanase from the pathogenic fungus, Fusarium solani f.sp. phaseoli - purification and some properties. Biosci. Biotech. Biochem. 1993 57, 231-235.
- Cheng CY and Li YK. (2000). An Aspergillus chitosanase with potential for large-scale preparation of chitosan oligosaccharides. Biotechnol Appl Biochem. 2000;32(3):197-203. DOI:10.1042/ba20000063 |
- Cheng CY, Chang CH, Wu YJ, and Li YK. (2006). Exploration of glycosyl hydrolase family 75, a chitosanase from Aspergillus fumigatus. J Biol Chem. 2006;281(6):3137-44. DOI:10.1074/jbc.M512506200 |
- Shimosaka M, Sato K, Nishiwaki N, Miyazawa T, and Okazaki M. (2005). Analysis of essential carboxylic amino acid residues for catalytic activity of fungal chitosanases by site-directed mutagenesis. J Biosci Bioeng. 2005;100(5):545-50. DOI:10.1263/jbb.100.545 |
-
Shimosaka M, Kumehara M, Zhang X-Y, Nogawa M, and Okazaki M. Cloning and characterization of a chitosanase gene from the plant pathogenic fungus Fusarium solani. J. Ferment. Bioeng. 1996 82, 426-431.