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1qin

From Proteopedia

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{{STRUCTURE_1qin| PDB=1qin | SCENE= }}
{{STRUCTURE_1qin| PDB=1qin | SCENE= }}
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'''HUMAN GLYOXALASE I COMPLEXED WITH S-(N-HYDROXY-N-P-IODOPHENYLCARBAMOYL) GLUTATHIONE'''
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===HUMAN GLYOXALASE I COMPLEXED WITH S-(N-HYDROXY-N-P-IODOPHENYLCARBAMOYL) GLUTATHIONE===
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==Overview==
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The structures of human glyoxalase I in complexes with S-(N-hydroxy-N-p-iodophenylcarbamoyl)glutathione (HIPC-GSH) and S-p-nitrobenzyloxycarbonylglutathione (NBC-GSH) have been determined at 2.0 and 1.72 A resolution, respectively. HIPC-GSH is a transition state analogue mimicking the enediolate intermediate that forms along the reaction pathway of glyoxalase I. In the structure, the hydroxycarbamoyl function is directly coordinated to the active site zinc ion. In contrast, the equivalent group in the NBC-GSH complex is approximately 6 A from the metal in a conformation that may resemble the product complex with S-D-lactoylglutathione. In this complex, two water molecules occupy the liganding positions at the zinc ion occupied by the hydroxycarbamoyl function in the enediolate analogue complex. Coordination of the transition state analogue to the metal enables a loop to close down over the active site, relative to its position in the product-like structure, allowing the glycine residue of the glutathione moiety to hydrogen bond with the protein. The structure of the complex with the enediolate analogue supports an "inner sphere mechanism" in which the GSH-methylglyoxal thiohemiacetal substrate is converted to product via a cis-enediolate intermediate. The zinc ion is envisioned to play an electrophilic role in catalysis by directly coordinating this intermediate. In addition, the carboxyl of Glu 172 is proposed to be displaced from the inner coordination sphere of the metal ion during substrate binding, thus allowing this group to facilitate proton transfer between the adjacent carbon atoms of the substrate. This proposal is supported by the observation that in the complex with the enediolate analogue the carboxyl group of Glu 172 is 3.3 A from the metal and is in an ideal position for reprotonation of the transition state intermediate. In contrast, Glu 172 is directly coordinated to the zinc ion in the complexes with S-benzylglutathione and with NBC-GSH.
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{{ABSTRACT_PUBMED_10521255}}
==About this Structure==
==About this Structure==
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[[Category: Lactoylglutathione lyase]]
[[Category: Lactoylglutathione lyase]]
[[Category: Lyase]]
[[Category: Lyase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 04:18:46 2008''

Revision as of 01:18, 29 July 2008

Image:1qin.png

Template:STRUCTURE 1qin

HUMAN GLYOXALASE I COMPLEXED WITH S-(N-HYDROXY-N-P-IODOPHENYLCARBAMOYL) GLUTATHIONE

Template:ABSTRACT PUBMED 10521255

About this Structure

1QIN is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

Reference

Reaction mechanism of glyoxalase I explored by an X-ray crystallographic analysis of the human enzyme in complex with a transition state analogue., Cameron AD, Ridderstrom M, Olin B, Kavarana MJ, Creighton DJ, Mannervik B, Biochemistry. 1999 Oct 12;38(41):13480-90. PMID:10521255

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