2qmc

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{{STRUCTURE_2qmc| PDB=2qmc | SCENE= }}
{{STRUCTURE_2qmc| PDB=2qmc | SCENE= }}
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'''Crystal Structure of Helicobacter Pylori Gamma-Glutamyltranspeptidase T380A Mutant'''
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===Crystal Structure of Helicobacter Pylori Gamma-Glutamyltranspeptidase T380A Mutant===
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==Overview==
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Helicobacter pylori gamma-glutamyltranspeptidase (HpGT) is a member of the N-terminal nucleophile hydrolase superfamily. It is translated as an inactive 60 kDa polypeptide precursor that undergoes intramolecular autocatalytic cleavage to generate a fully active heterodimer composed of a 40 kDa and a 20 kDa subunit. The resultant N-terminus, Thr 380, has been shown to be the catalytic nucleophile in both autoprocessing and enzymatic reactions. Once processed, HpGT catalyzes the hydrolysis of the gamma-glutamyl bond in glutathione and its conjugates. To facilitate the determination of physiologically relevant substrates for the enzyme, crystal structures of HpGT in complex with glutamate (1.6 A, Rfactor = 16.7%, Rfree = 19.0%) and an inactive HpGT mutant, T380A, in complex with S-(nitrobenzyl)glutathione (1.55 A, Rfactor = 18.7%, Rfree = 21.8%) have been determined. Residues that comprise the gamma-glutamyl binding site are primarily located in the 20 kDa subunit and make numerous hydrogen bonds with the alpha-amino and alpha-carboxylate groups of the substrate. In contrast, a single hydrogen bond occurs between the T380A mutant and the remainder of the ligand. Lack of specific coordination beyond the gamma-glutamyl moiety may account for the substrate binding permissiveness of the enzyme. Structural analysis was combined with site-directed mutagenesis of residues involved in maintaining the conformation of a loop region that covers the gamma-glutamyl binding site. Results provide evidence that access to this buried site may occur through conformational changes in the Tyr 433-containing loop, as disruption of the intricate hydrogen-bond network responsible for optimal placement of Tyr 433 significantly diminishes catalytic activity.
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(as it appears on PubMed at http://www.pubmed.gov), where 17960917 is the PubMed ID number.
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{{ABSTRACT_PUBMED_17960917}}
==About this Structure==
==About this Structure==
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==Reference==
==Reference==
Characterization of Helicobacter pylori gamma-glutamyltranspeptidase reveals the molecular basis for substrate specificity and a critical role for the tyrosine 433-containing loop in catalysis., Morrow AL, Williams K, Sand A, Boanca G, Barycki JJ, Biochemistry. 2007 Nov 20;46(46):13407-14. Epub 2007 Oct 26. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/17960917 17960917]
Characterization of Helicobacter pylori gamma-glutamyltranspeptidase reveals the molecular basis for substrate specificity and a critical role for the tyrosine 433-containing loop in catalysis., Morrow AL, Williams K, Sand A, Boanca G, Barycki JJ, Biochemistry. 2007 Nov 20;46(46):13407-14. Epub 2007 Oct 26. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/17960917 17960917]
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Autoprocessing of Helicobacter pylori gamma-glutamyltranspeptidase leads to the formation of a threonine-threonine catalytic dyad., Boanca G, Sand A, Okada T, Suzuki H, Kumagai H, Fukuyama K, Barycki JJ, J Biol Chem. 2007 Jan 5;282(1):534-41. Epub 2006 Nov 15. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/17107958 17107958]
[[Category: Gamma-glutamyltransferase]]
[[Category: Gamma-glutamyltransferase]]
[[Category: Helicobacter pylori]]
[[Category: Helicobacter pylori]]
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[[Category: Ntn-hydrolase]]
[[Category: Ntn-hydrolase]]
[[Category: Transferase]]
[[Category: Transferase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 15:11:50 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 22:08:17 2008''

Revision as of 19:08, 27 July 2008

Image:2qmc.png

Template:STRUCTURE 2qmc

Crystal Structure of Helicobacter Pylori Gamma-Glutamyltranspeptidase T380A Mutant

Template:ABSTRACT PUBMED 17960917

About this Structure

2QMC is a Protein complex structure of sequences from Helicobacter pylori. Full crystallographic information is available from OCA.

Reference

Characterization of Helicobacter pylori gamma-glutamyltranspeptidase reveals the molecular basis for substrate specificity and a critical role for the tyrosine 433-containing loop in catalysis., Morrow AL, Williams K, Sand A, Boanca G, Barycki JJ, Biochemistry. 2007 Nov 20;46(46):13407-14. Epub 2007 Oct 26. PMID:17960917

Autoprocessing of Helicobacter pylori gamma-glutamyltranspeptidase leads to the formation of a threonine-threonine catalytic dyad., Boanca G, Sand A, Okada T, Suzuki H, Kumagai H, Fukuyama K, Barycki JJ, J Biol Chem. 2007 Jan 5;282(1):534-41. Epub 2006 Nov 15. PMID:17107958

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