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Difference between revisions of "Glycoside Hydrolase Family 125"
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== Substrate specificities == | == Substrate specificities == | ||
| − | The currently characterized family 125 glycoside hydrolyses, which include the examples from ''Streptococcus pneumoniae'' (SpGH125) and ''Clostridium perfringens'' (CpGH125), are | + | The currently characterized family 125 glycoside hydrolyses, which include the examples from ''Streptococcus pneumoniae'' (SpGH125) and ''Clostridium perfringens'' (CpGH125), are α-mannosidases with specificity for α-1,6-linked non-reducing terminal mannose residues <cite>Gregg2011</cite>. |
== Kinetics and Mechanism == | == Kinetics and Mechanism == | ||
| − | Kinetic characterization of 2,4-dinitrophenyl | + | Kinetic characterization of 2,4-dinitrophenyl α-D-mannopyranoside hydrolysis by SpGH125 and Cp125 revealed that this is a poor substrate for these enzymes. Monitoring the hydrolysis of methyl 6-''O''-(α-D-mannopyranosyl)-β-D-mannopyranoside by sup>1</sup>H NMR spectroscopy revealed that CpGH125 and SpGH125 act with inversion of stereochemistry. The structural analysis of both enzymes reveal an arrangement of catalytic residues that is consistent with this mechanistic assignment <cite>Gregg2011</cite>. |
== Catalytic Residues == | == Catalytic Residues == | ||
| − | + | The structural analysis of CpGH125 suggests it uses aspartate 220 as a catalytic acid and glutamate 393 as catalytic base. The corresponding residues in SpGH125 are aspartame 218 and glutamate 391. | |
| − | |||
== Three-dimensional structures == | == Three-dimensional structures == | ||
| − | + | The three dimensional structures of CpGH125 [{{PDBlink}}3qt3 3qt3], [{{PDBlink}}3qt9 3qt9], [{{PDBlink}}2nvp 2nvp] and [{{PDBlink}}2vcc 2vcc] <cite>1</cite>. | |
== Family Firsts == | == Family Firsts == | ||
| − | ;First stereochemistry determination: <sup>1</sup>H NMR spectroscopy revealed that CpGH125 and SpGH125 act with inversion of stereochemistry <cite>Gregg2011</cite> | + | ;First stereochemistry determination: <sup>1</sup>H NMR spectroscopy revealed that CpGH125 and SpGH125 act with inversion of stereochemistry <cite>Gregg2011</cite>. |
;First catalytic nucleophile identification: Cite some reference here, with a ''short'' (1-2 sentence) explanation <cite>Sinnott1990</cite>. | ;First catalytic nucleophile identification: Cite some reference here, with a ''short'' (1-2 sentence) explanation <cite>Sinnott1990</cite>. | ||
;First general acid/base residue identification: Cite some reference here, with a ''short'' (1-2 sentence) explanation <cite>He1999</cite>. | ;First general acid/base residue identification: Cite some reference here, with a ''short'' (1-2 sentence) explanation <cite>He1999</cite>. | ||
Revision as of 10:16, 16 November 2012
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: ^^^Alisdair Boraston^^^
- Responsible Curator: ^^^Alisdair Boraston^^^
| Glycoside Hydrolase Family GH125 | |
| Clan | GH-L |
| Mechanism | inverting |
| Active site residues | known |
| CAZy DB link | |
| http://www.cazy.org/GH125.html | |
Substrate specificities
The currently characterized family 125 glycoside hydrolyses, which include the examples from Streptococcus pneumoniae (SpGH125) and Clostridium perfringens (CpGH125), are α-mannosidases with specificity for α-1,6-linked non-reducing terminal mannose residues [1].
Kinetics and Mechanism
Kinetic characterization of 2,4-dinitrophenyl α-D-mannopyranoside hydrolysis by SpGH125 and Cp125 revealed that this is a poor substrate for these enzymes. Monitoring the hydrolysis of methyl 6-O-(α-D-mannopyranosyl)-β-D-mannopyranoside by sup>1H NMR spectroscopy revealed that CpGH125 and SpGH125 act with inversion of stereochemistry. The structural analysis of both enzymes reveal an arrangement of catalytic residues that is consistent with this mechanistic assignment [1].
Catalytic Residues
The structural analysis of CpGH125 suggests it uses aspartate 220 as a catalytic acid and glutamate 393 as catalytic base. The corresponding residues in SpGH125 are aspartame 218 and glutamate 391.
Three-dimensional structures
The three dimensional structures of CpGH125 3qt3, 3qt9, 2nvp and 2vcc [2].
Family Firsts
- First stereochemistry determination
- 1H NMR spectroscopy revealed that CpGH125 and SpGH125 act with inversion of stereochemistry [1].
- First catalytic nucleophile identification
- Cite some reference here, with a short (1-2 sentence) explanation [3].
- First general acid/base residue identification
- Cite some reference here, with a short (1-2 sentence) explanation [4].
- First 3-D structure
- Cite some reference here, with a short (1-2 sentence) explanation [5].
References
- Gregg KJ, Zandberg WF, Hehemann JH, Whitworth GE, Deng L, Vocadlo DJ, and Boraston AB. (2011). Analysis of a new family of widely distributed metal-independent alpha-mannosidases provides unique insight into the processing of N-linked glycans. J Biol Chem. 2011;286(17):15586-96. DOI:10.1074/jbc.M111.223172 |