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Difference between revisions of "Glycoside Hydrolase Family 116"

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== Catalytic Residues ==
 
== Catalytic Residues ==
  
The catalytic residues were identified in the ''S. solfataricus'' β-glucosidase <cite>PMID20427274</cite>. The [[catalytic nucleophile]] was identified as Glu335 in the sequence AIY'''E'''AP through trapping of the 2,4-deoxy-2-fluoroglucosyl-enzyme [[intermediate]] and MS/MS analysis. The [[general acid/base]] catalyst role was assigned to Asp462 through mechanistic analysis, which included azide rescue experiments, of a mutant at that position.
+
The catalytic residues were identified in the ''S. solfataricus'' β-glucosidase <cite>PMID20427274</cite>. The [[catalytic nucleophile]] was identified as Glu335 in the sequence AIY'''<u>E</u>'''AP through trapping of the 2,4-deoxy-2-fluoroglucosyl-enzyme [[intermediate]] and MS/MS analysis. The [[general acid/base]] catalyst role was assigned to Asp462 through mechanistic analysis, which included azide rescue experiments, of a mutant at that position.
  
  

Revision as of 05:34, 18 June 2010

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Glycoside Hydrolase Family GH116
Clan none
Mechanism retaining
Active site residues known
CAZy DB link
http://www.cazy.org/GH116.html


Substrate specificities

This family of glycoside hydrolases was recently discovered characterising a new β-glucosidase from the hyperthermophilic archaeon Sulfolobus solfataricus [1]. This enzyme is distantly related to the human non-lysosomal bile acid β-glucosidase GBA2, also known as glucocerebrosidase [2]. GH116 contains acid β-glucosidase (EC 3.2.1.45), β-glucosidase (EC 3.2.1.21) and β-xylosidase (EC 3.2.1.37) activities from the three domains of life.


Kinetics and Mechanism

The enzymes of this family are retaining glycoside hydrolases, and follow the classical Koshland double-displacement mechanism [3]. The stereochemistry of hydrolysis has been demonstrated by NMR using 4NP-β-Xyl as the substrate and S. solfataricus SSO1353 as the enzyme [1].


Catalytic Residues

The catalytic residues were identified in the S. solfataricus β-glucosidase [1]. The catalytic nucleophile was identified as Glu335 in the sequence AIYEAP through trapping of the 2,4-deoxy-2-fluoroglucosyl-enzyme intermediate and MS/MS analysis. The general acid/base catalyst role was assigned to Asp462 through mechanistic analysis, which included azide rescue experiments, of a mutant at that position.


Three-dimensional structures

Unkwown


Family Firsts

First stereochemistry determination
Sulfolobus solfataricus β-glucosidase by NMR [1].
First catalytic nucleophile identification
Sulfolobus solfataricus β-glucosidase by 2,4-deoxy-2-fluoroglucose labeling [1].
First general acid/base residue identification
Sulfolobus solfataricus β-glucosidase by azide rescue with mutant [1].
First 3-D structure

References

  1. Cobucci-Ponzano B, Aurilia V, Riccio G, Henrissat B, Coutinho PM, Strazzulli A, Padula A, Corsaro MM, Pieretti G, Pocsfalvi G, Fiume I, Cannio R, Rossi M, and Moracci M. (2010). A new archaeal beta-glycosidase from Sulfolobus solfataricus: seeding a novel retaining beta-glycan-specific glycoside hydrolase family along with the human non-lysosomal glucosylceramidase GBA2. J Biol Chem. 2010;285(27):20691-703. DOI:10.1074/jbc.M109.086470 | PubMed ID:20427274 [PMID20427274]
  2. Boot RG, Verhoek M, Donker-Koopman W, Strijland A, van Marle J, Overkleeft HS, Wennekes T, and Aerts JM. (2007). Identification of the non-lysosomal glucosylceramidase as beta-glucosidase 2. J Biol Chem. 2007;282(2):1305-12. DOI:10.1074/jbc.M610544200 | PubMed ID:17105727 [PMID17105727]
  3. Koshland DE Jr: Stereochemistry and the mechanism of enzyme reactions. Biol Rev 1953, 28:416-436.

    [Koshland]

All Medline abstracts: PubMed