2jbv

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{{STRUCTURE_2jbv| PDB=2jbv | SCENE= }}
{{STRUCTURE_2jbv| PDB=2jbv | SCENE= }}
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'''CRYSTAL STRUCTURE OF CHOLINE OXIDASE REVEALS INSIGHTS INTO THE CATALYTIC MECHANISM'''
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===CRYSTAL STRUCTURE OF CHOLINE OXIDASE REVEALS INSIGHTS INTO THE CATALYTIC MECHANISM===
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==Overview==
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Choline oxidase catalyzes the oxidation of choline to glycine betaine, a compatible solute that accumulates in pathogenic bacteria and plants so they can withstand osmotic and temperature stresses. The crystal structure of choline oxidase was determined and refined to a resolution of 1.86 A with data collected at 100 K using synchrotron X-ray radiation. The structure reveals a covalent linkage between His99 Nepsilon2 and FAD C8M atoms, and a 123 A3 solvent-excluded cavity adjacent to the re face of the flavin. A hypothetical model for choline docked into the cavity suggests that several aromatic residues and Glu312 may orient the cationic substrate for efficient catalysis. The role of the negative charge on Glu312 was investigated by engineering variant enzymes in which Glu312 was replaced with alanine, glutamine, or aspartate. The Glu312Ala enzyme was inactive. The Glu312Gln enzyme exhibited a Kd value for choline at least 500 times larger than that of the wild-type enzyme. The Glu312Asp enzyme had a kcat/KO2 value similar to that of the wild-type enzyme but kcat and kcat/Km values that were 230 and 35 times lower, respectively, than in the wild-type enzyme. These data are consistent with the spatial location of the negative charge on residue 312 being important for the oxidation of the alcohol substrate. Solvent viscosity and substrate kinetic isotope effects suggest the presence of an internal equilibrium in the Glu312Asp enzyme prior to the hydride transfer reaction. Altogether, the crystallographic and mechanistic data suggest that Glu312 is important for binding and positioning of the substrate in the active site of choline oxidase.
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The line below this paragraph, {{ABSTRACT_PUBMED_18072756}}, adds the Publication Abstract to the page
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(as it appears on PubMed at http://www.pubmed.gov), where 18072756 is the PubMed ID number.
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{{ABSTRACT_PUBMED_18072756}}
==About this Structure==
==About this Structure==
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==Reference==
==Reference==
Role of Glu312 in binding and positioning of the substrate for the hydride transfer reaction in choline oxidase., Quaye O, Lountos GT, Fan F, Orville AM, Gadda G, Biochemistry. 2008 Jan 8;47(1):243-56. Epub 2007 Dec 12. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/18072756 18072756]
Role of Glu312 in binding and positioning of the substrate for the hydride transfer reaction in choline oxidase., Quaye O, Lountos GT, Fan F, Orville AM, Gadda G, Biochemistry. 2008 Jan 8;47(1):243-56. Epub 2007 Dec 12. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/18072756 18072756]
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Cloning, sequence analysis, and purification of choline oxidase from Arthrobacter globiformis: a bacterial enzyme involved in osmotic stress tolerance., Fan F, Ghanem M, Gadda G, Arch Biochem Biophys. 2004 Jan 1;421(1):149-58. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/14678796 14678796]
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Kinetic mechanism of choline oxidase from Arthrobacter globiformis., Gadda G, Biochim Biophys Acta. 2003 Mar 21;1646(1-2):112-8. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/12637017 12637017]
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The trimethylammonium headgroup of choline is a major determinant for substrate binding and specificity in choline oxidase., Gadda G, Powell NL, Menon P, Arch Biochem Biophys. 2004 Oct 15;430(2):264-73. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/15369826 15369826]
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On the catalytic mechanism of choline oxidase., Fan F, Gadda G, J Am Chem Soc. 2005 Feb 23;127(7):2067-74. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/15713082 15713082]
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On the catalytic role of the conserved active site residue His466 of choline oxidase., Ghanem M, Gadda G, Biochemistry. 2005 Jan 25;44(3):893-904. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/15654745 15654745]
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Effects of reversing the protein positive charge in the proximity of the flavin N(1) locus of choline oxidase., Ghanem M, Gadda G, Biochemistry. 2006 Mar 14;45(10):3437-47. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/16519539 16519539]
[[Category: Arthrobacter globiformis]]
[[Category: Arthrobacter globiformis]]
[[Category: Choline oxidase]]
[[Category: Choline oxidase]]
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[[Category: Glucose-methanol-choline oxidoreductase enzyme superfamily]]
[[Category: Glucose-methanol-choline oxidoreductase enzyme superfamily]]
[[Category: Oxidoreductase]]
[[Category: Oxidoreductase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 08:39:48 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 16:29:19 2008''

Revision as of 13:29, 28 July 2008

Image:2jbv.png

Template:STRUCTURE 2jbv

CRYSTAL STRUCTURE OF CHOLINE OXIDASE REVEALS INSIGHTS INTO THE CATALYTIC MECHANISM

Template:ABSTRACT PUBMED 18072756

About this Structure

2JBV is a Single protein structure of sequence from Arthrobacter globiformis. Full crystallographic information is available from OCA.

Reference

Role of Glu312 in binding and positioning of the substrate for the hydride transfer reaction in choline oxidase., Quaye O, Lountos GT, Fan F, Orville AM, Gadda G, Biochemistry. 2008 Jan 8;47(1):243-56. Epub 2007 Dec 12. PMID:18072756

Cloning, sequence analysis, and purification of choline oxidase from Arthrobacter globiformis: a bacterial enzyme involved in osmotic stress tolerance., Fan F, Ghanem M, Gadda G, Arch Biochem Biophys. 2004 Jan 1;421(1):149-58. PMID:14678796

Kinetic mechanism of choline oxidase from Arthrobacter globiformis., Gadda G, Biochim Biophys Acta. 2003 Mar 21;1646(1-2):112-8. PMID:12637017

The trimethylammonium headgroup of choline is a major determinant for substrate binding and specificity in choline oxidase., Gadda G, Powell NL, Menon P, Arch Biochem Biophys. 2004 Oct 15;430(2):264-73. PMID:15369826

On the catalytic mechanism of choline oxidase., Fan F, Gadda G, J Am Chem Soc. 2005 Feb 23;127(7):2067-74. PMID:15713082

On the catalytic role of the conserved active site residue His466 of choline oxidase., Ghanem M, Gadda G, Biochemistry. 2005 Jan 25;44(3):893-904. PMID:15654745

Effects of reversing the protein positive charge in the proximity of the flavin N(1) locus of choline oxidase., Ghanem M, Gadda G, Biochemistry. 2006 Mar 14;45(10):3437-47. PMID:16519539

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