Glycoside Hydrolase Family 115

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• Author: ^^^Satoshi Kaneko^^^
• Responsible Curator: ^^^Satoshi Kaneko^^^

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Glycoside Hydrolase Family GH115
Clan	GH-x
Mechanism	inverting
Active site residues	not known
CAZy DB link
http://www.cazy.org/GH115.html

Substrate specificities

Glycoside hydrolases of this family display alpha-glucuronidase activity. The enzymes possible to release 4-O-methyl D-glucuronic acid from polymeric xylans. The substrate specificity could be distinguished from GH67 enzymes. In contrast to GH67 enzymes which only cleave glucuronosyl linkage at the non-reducing end of xylooligosaccharides, GH115 enzymes remove glucuronic acid from the both terminal and internal regions of xylooligosaccharides and xylans. This kind of substrate specificty firstly demonstrated by an alpha-glucuronidase purified from Thermoascus aurantiacus [1] and N-terminal amino acid sequence of Schizophyllum commune firstly provided [2]. In spite of the N-terminal amino acid sequence of Pichia stipitis did not show significant similarity with the sequence of S. commune, the information lead to find full amino acid sequence and establish this family [3]. It has been demonstrated that these enzymes release 4-O-methyl D-glucuronic acid, the enzyme from Streptomyces pristinaespiralis produced the both 4-O-methyl D-glucuronic acid and non methylated D-glucuronic acid as the reaction product [4].

Kinetics and Mechanism

Using 1H NMR spectroscopy and reduced aldopentaouronic acid(MeGlcA3Xyl4-ol) as a substrate, it was demonstrated that both the enzymes from S. commune and P. stipitis releasing 4-O-methyl-D-glucuronic acid (MeGlcA) as its beta-anomer, suggesting a single displacement mechanism [5].

Catalytic Residues

Not identified.

Three-dimensional structures

No 3D-structure is solved for this family of enzyme.

Family Firsts

First stereochemistry determination

1H NMR demonstrated that the released 4-methyl-D-glucuronic acid was a beta anomer and thus that the enzyme is an inverter [5].

First catalytic nucleophile identification

unproved.

First general acid/base residue identification

unproved.

First 3-D structure

Just crystallization of S. pristinaespiralis enzyme is reported [4].

References

1. Khandke KM, Vithayathil PJ, and Murthy SK. (1989). Purification and characterization of an alpha-D-glucuronidase from a thermophilic fungus, Thermoascus aurantiacus. Arch Biochem Biophys. 1989;274(2):511-7. DOI:10.1016/0003-9861(89)90464-5 |
2. Tenkanen M and Siika-aho M. (2000). An alpha-glucuronidase of Schizophyllum commune acting on polymeric xylan. J Biotechnol. 2000;78(2):149-61. DOI:10.1016/s0168-1656(99)00240-0 |
3. Ryabova O, Vrsanská M, Kaneko S, van Zyl WH, and Biely P. (2009). A novel family of hemicellulolytic alpha-glucuronidase. FEBS Lett. 2009;583(9):1457-62. DOI:10.1016/j.febslet.2009.03.057 |