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Difference between revisions of "Glycoside Hydrolase Family 46"
| Line 35: | Line 35: | ||
== Kinetics and Mechanism == | == Kinetics and Mechanism == | ||
| − | + | Family GH46 enzymes utilize an inverting mechanism, as shown by NMR <cite>Fukamizo1995</cite>. | |
== Catalytic Residues == | == Catalytic Residues == | ||
| − | + | The catalytic residues have been identified by site-directed mutagenesis and crystallography in the chitosanase from Streptomyces sp. N174. The general acid residue is Glu22, while Asp40 is the general base residue <cite>Boucher1995 Marcotte1996</cite>. The latter could activate the nucleophilic water molecule with assistance from residue Thr45 <cite>Lacombe-Harvey2009</cite>. | |
| Line 57: | Line 57: | ||
#Boucher1992 Boucher, I., Dupuy, A., Vidal, P., Neugebauer, W. A., Brzezinski, R. (1992) Purification and characterization of a chitosanase from ''Streptomyces'' N174. Applied Microbiology and Biotechnology 38:188-193. | #Boucher1992 Boucher, I., Dupuy, A., Vidal, P., Neugebauer, W. A., Brzezinski, R. (1992) Purification and characterization of a chitosanase from ''Streptomyces'' N174. Applied Microbiology and Biotechnology 38:188-193. | ||
#Mitsutomi1996 Mitsutomi, M., Ueda, M., Arai, M., Ando, A., Watanabe, T. (1996) Action patterns of microbial chitinases and chitosanases on partially ''N''-acetylated chitosan. Chitin Enzymology, vol. 2, pp 273-284. | #Mitsutomi1996 Mitsutomi, M., Ueda, M., Arai, M., Ando, A., Watanabe, T. (1996) Action patterns of microbial chitinases and chitosanases on partially ''N''-acetylated chitosan. Chitin Enzymology, vol. 2, pp 273-284. | ||
| − | #Fukamizo1995 | + | #Fukamizo1995 pmid=7487871 |
| + | #Boucher1995 pmid=8537367 | ||
| + | #Lacombe-Harvey2009 pmid=19143844 | ||
</biblio> | </biblio> | ||
[[Category:Glycoside Hydrolase Families|GH046]] | [[Category:Glycoside Hydrolase Families|GH046]] | ||
Revision as of 11:50, 4 February 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: ^^^Ryszard Brzezinski^^^
- Responsible Curator: ^^^Ryszard Brzezinski^^^
| Glycoside Hydrolase Family GHnn | |
| Clan | GH-I |
| Mechanism | inverting |
| Active site residues | known |
| CAZy DB link | |
| http://www.cazy.org/fam/GH46.html | |
Substrate specificities
Glycoside hydrolases of family 46 are essentially endo-beta-1,4-chitosanases (EC 3.2.1.132) that hydrolyze various links in chitosan, a polymer of beta-1,4-linked D-glucosamine (GlcN) units with a variable content (mostly 0 - 35%) of N-acetyl-D-glucosamine (GlcNAc) [1, 2]. Among the four types of links occurring between these two kinds of subunits in chitosan, all the enzymes examined for their cleavage specificity recognized productively the GlcN-GlcN links. Furthermore, the chitosanase from Bacillus circulans MH-K1 recognized also GlcN-GlcNAc links [3], while the chitosanase from Streptomyces sp. N174 recognized the GlcNAc-GlcN links [4].
Kinetics and Mechanism
Family GH46 enzymes utilize an inverting mechanism, as shown by NMR [4].
Catalytic Residues
The catalytic residues have been identified by site-directed mutagenesis and crystallography in the chitosanase from Streptomyces sp. N174. The general acid residue is Glu22, while Asp40 is the general base residue [5, 6]. The latter could activate the nucleophilic water molecule with assistance from residue Thr45 [7].
Three-dimensional structures
Content is to be added here.
Family Firsts
- First sterochemistry determination
- Cite some reference here, with a short (1-2 sentence) explanation (citation).
- First catalytic nucleophile identification
- Cite some reference here, with a short (1-2 sentence) explanation (citation).
- First general acid/base residue identification
- Cite some reference here, with a short (1-2 sentence) explanation (citation).
- First 3-D structure
- Cite some reference here, with a short (1-2 sentence) explanation (citation).
References
-
Yabuki, M., Uchiyama, A., Suzuki, K., Ando, A., Fujii, T. (1988) Purification and properties of chitosanase from Bacillus circulans MH-K1. Journal of General and Applied Microbiology 34:255-270.
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Boucher, I., Dupuy, A., Vidal, P., Neugebauer, W. A., Brzezinski, R. (1992) Purification and characterization of a chitosanase from Streptomyces N174. Applied Microbiology and Biotechnology 38:188-193.
-
Mitsutomi, M., Ueda, M., Arai, M., Ando, A., Watanabe, T. (1996) Action patterns of microbial chitinases and chitosanases on partially N-acetylated chitosan. Chitin Enzymology, vol. 2, pp 273-284.
- Fukamizo T, Honda Y, Goto S, Boucher I, and Brzezinski R. (1995). Reaction mechanism of chitosanase from Streptomyces sp. N174. Biochem J. 1995;311 ( Pt 2)(Pt 2):377-83. DOI:10.1042/bj3110377 |
- Boucher I, Fukamizo T, Honda Y, Willick GE, Neugebauer WA, and Brzezinski R. (1995). Site-directed mutagenesis of evolutionary conserved carboxylic amino acids in the chitosanase from Streptomyces sp. N174 reveals two residues essential for catalysis. J Biol Chem. 1995;270(52):31077-82. DOI:10.1074/jbc.270.52.31077 |
- Lacombe-Harvey ME, Fukamizo T, Gagnon J, Ghinet MG, Dennhart N, Letzel T, and Brzezinski R. (2009). Accessory active site residues of Streptomyces sp. N174 chitosanase: variations on a common theme in the lysozyme superfamily. FEBS J. 2009;276(3):857-69. DOI:10.1111/j.1742-4658.2008.06830.x |