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Glycoside Hydrolase Family 115

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Glycoside Hydrolase Family GH115
Clan none
Mechanism inverting
Active site residues not known
CAZy DB link
http://www.cazy.org/GH115.html


Substrate specificities

Glycoside hydrolases of GH115 display α-glucuronidase activity. In particular, members of this family catalyze the cleavage of 4-O-methyl D-glucuronic acid sidechains from native xylan polysaccharides (EC 3.2.1.131). In contrast to GH67 enzymes, which only cleave glucuronosyl linkages at the non-reducing ends of xylooligosaccharides, GH115 enzymes remove glucuronic acid from the both terminal and internal regions of xylooligosaccharides and xylans [1]. This substrate specificity was first demonstrated by an α-glucuronidase purified from Thermoascus aurantiacus [2], and later for a Schizophyllum commune α-glucuronidase [3]. Although GH115 was established on the basis of biochemical and sequence analysis of Pichia stipitis (4-O-methyl)-α-glucuronidase [1], available N-terminal protein sequence of the S. commune enzyme [3] allowed the tentative assignment of this enzyme to GH115 [1], which was later confirmed by the full protein sequence [4]. A GH115 member from Streptomyces pristinaespiralis produces both 4-O-methyl-D-glucuronic acid and non-methylated D-glucuronic acid from xylan and xylo-oligosaccharides [5].

Kinetics and Mechanism

Using reduced aldopentauronic acid (MeGlcA3Xyl4-ol) as a substrate, analysis by 1H-NMR spectroscopy revealed that the enzymes from both S. commune and P. stipitis release the β-anomer of 4-O-methyl-D-glucuronic acid (MeGlcA) as the first-formed product, thus suggesting a one step, inverting mechanism [6].

Catalytic Residues

The catalytic residues have not yet been identified in a member of this family.

Three-dimensional structures

No 3D structure has been solved for this family at present, although crystallization of a Streptomyces pristinaespiralis homolog has been reported [5].

Family Firsts

First stereochemistry determination
Release of the β-anomer of 4-methyl-D-glucuronic acid by both the Schizophyllum commune and Pichia stipitis enzymes using 1H NMR [6].
First general acid residue identification
Not yet identified.
First general base residue identification
Not yet identified.
First 3-D structure
Crystallization of the Streptomyces pristinaespiralis family member has been reported [5].

References

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  1. Error fetching PMID 19344716: [Ryabova2009]
  2. Error fetching PMID 2802623: [Khandke1989]
  3. Error fetching PMID 10725538: [Tenkanen2000]
  4. Error fetching PMID 21442271: [Chong2011]
  5. Error fetching PMID 21206027: [Fujimoto2011]
  6. Error fetching PMID 20804758: [Kolenova2010]
All Medline abstracts: PubMed | HubMed