1i19

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(New page: 200px<br /><applet load="1i19" size="450" color="white" frame="true" align="right" spinBox="true" caption="1i19, resolution 1.70&Aring;" /> '''CRYSTAL STRUCTURE OF...)
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caption="1i19, resolution 1.70&Aring;" />
caption="1i19, resolution 1.70&Aring;" />
'''CRYSTAL STRUCTURE OF CHOLESTEROL OXIDASE FROM B.STEROLICUM'''<br />
'''CRYSTAL STRUCTURE OF CHOLESTEROL OXIDASE FROM B.STEROLICUM'''<br />
==Overview==
==Overview==
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Cholesterol oxidase is a monomeric flavoenzyme that catalyzes the, oxidation and isomerization of cholesterol to cholest-4-en-3-one. Two, forms of the enzyme are known, one containing the cofactor non-covalently, bound to the protein and one in which the cofactor is covalently linked to, a histidine residue. The x-ray structure of the enzyme from Brevibacterium, sterolicum containing covalently bound FAD has been determined and refined, to 1.7-A resolution. The active site consists of a cavity sealed off from, the exterior of the protein. A model for the steroid substrate, cholesterol, can be positioned in the pocket revealing the structural, factors that result in different substrate binding affinities between the, two known forms of the enzyme. The structure suggests that Glu(475), located at the active site cavity, may act as the base for both the, oxidation and the isomerization steps of the catalytic reaction. A, water-filled channel extending toward the flavin moiety, inside the, substrate-binding cavity, may act as the entry point for molecular oxygen, for the oxidative half-reaction. An arginine and a glutamate residue at, the active site, found in two conformations are proposed to control oxygen, access to the cavity from the channel. These concerted side chain, movements provide an explanation for the biphasic mode of reaction with, dioxygen and the ping-pong kinetic mechanism exhibited by the enzyme.
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Cholesterol oxidase is a monomeric flavoenzyme that catalyzes the oxidation and isomerization of cholesterol to cholest-4-en-3-one. Two forms of the enzyme are known, one containing the cofactor non-covalently bound to the protein and one in which the cofactor is covalently linked to a histidine residue. The x-ray structure of the enzyme from Brevibacterium sterolicum containing covalently bound FAD has been determined and refined to 1.7-A resolution. The active site consists of a cavity sealed off from the exterior of the protein. A model for the steroid substrate, cholesterol, can be positioned in the pocket revealing the structural factors that result in different substrate binding affinities between the two known forms of the enzyme. The structure suggests that Glu(475), located at the active site cavity, may act as the base for both the oxidation and the isomerization steps of the catalytic reaction. A water-filled channel extending toward the flavin moiety, inside the substrate-binding cavity, may act as the entry point for molecular oxygen for the oxidative half-reaction. An arginine and a glutamate residue at the active site, found in two conformations are proposed to control oxygen access to the cavity from the channel. These concerted side chain movements provide an explanation for the biphasic mode of reaction with dioxygen and the ping-pong kinetic mechanism exhibited by the enzyme.
==About this Structure==
==About this Structure==
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1I19 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Brevibacterium_sterolicum Brevibacterium sterolicum] with MN, CAC, EDO and FAD as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cholesterol_oxidase Cholesterol oxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.3.6 1.1.3.6] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1I19 OCA].
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1I19 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Brevibacterium_sterolicum Brevibacterium sterolicum] with <scene name='pdbligand=MN:'>MN</scene>, <scene name='pdbligand=CAC:'>CAC</scene>, <scene name='pdbligand=EDO:'>EDO</scene> and <scene name='pdbligand=FAD:'>FAD</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cholesterol_oxidase Cholesterol oxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.3.6 1.1.3.6] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1I19 OCA].
==Reference==
==Reference==
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[[Category: Ghisla, S.]]
[[Category: Ghisla, S.]]
[[Category: Vrielink, A.]]
[[Category: Vrielink, A.]]
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[[Category: Yue, K.Q.]]
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[[Category: Yue, K Q.]]
[[Category: CAC]]
[[Category: CAC]]
[[Category: EDO]]
[[Category: EDO]]
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[[Category: mix alpha beta]]
[[Category: mix alpha beta]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Sun Nov 25 03:27:06 2007''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:06:57 2008''

Revision as of 11:07, 21 February 2008

Image:1i19.gif

1i19, resolution 1.70Å

Drag the structure with the mouse to rotate

CRYSTAL STRUCTURE OF CHOLESTEROL OXIDASE FROM B.STEROLICUM

Overview

Cholesterol oxidase is a monomeric flavoenzyme that catalyzes the oxidation and isomerization of cholesterol to cholest-4-en-3-one. Two forms of the enzyme are known, one containing the cofactor non-covalently bound to the protein and one in which the cofactor is covalently linked to a histidine residue. The x-ray structure of the enzyme from Brevibacterium sterolicum containing covalently bound FAD has been determined and refined to 1.7-A resolution. The active site consists of a cavity sealed off from the exterior of the protein. A model for the steroid substrate, cholesterol, can be positioned in the pocket revealing the structural factors that result in different substrate binding affinities between the two known forms of the enzyme. The structure suggests that Glu(475), located at the active site cavity, may act as the base for both the oxidation and the isomerization steps of the catalytic reaction. A water-filled channel extending toward the flavin moiety, inside the substrate-binding cavity, may act as the entry point for molecular oxygen for the oxidative half-reaction. An arginine and a glutamate residue at the active site, found in two conformations are proposed to control oxygen access to the cavity from the channel. These concerted side chain movements provide an explanation for the biphasic mode of reaction with dioxygen and the ping-pong kinetic mechanism exhibited by the enzyme.

About this Structure

1I19 is a Single protein structure of sequence from Brevibacterium sterolicum with , , and as ligands. Active as Cholesterol oxidase, with EC number 1.1.3.6 Full crystallographic information is available from OCA.

Reference

Oxygen access to the active site of cholesterol oxidase through a narrow channel is gated by an Arg-Glu pair., Coulombe R, Yue KQ, Ghisla S, Vrielink A, J Biol Chem. 2001 Aug 10;276(32):30435-41. Epub 2001 Jun 7. PMID:11397813

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