3cnj
From Proteopedia
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==About this Structure== | ==About this Structure== | ||
| - | 3CNJ is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/ | + | 3CNJ is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Bacteria Bacteria]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3CNJ OCA]. |
==Reference== | ==Reference== | ||
The Binding and Release of Oxygen and Hydrogen Peroxide Are Directed by a Hydrophobic Tunnel in Cholesterol Oxidase., Chen L, Lyubimov AY, Brammer L, Vrielink A, Sampson NS, Biochemistry. 2008 Apr 15;. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/18410129 18410129] | The Binding and Release of Oxygen and Hydrogen Peroxide Are Directed by a Hydrophobic Tunnel in Cholesterol Oxidase., Chen L, Lyubimov AY, Brammer L, Vrielink A, Sampson NS, Biochemistry. 2008 Apr 15;. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/18410129 18410129] | ||
| + | [[Category: Bacteria]] | ||
[[Category: Cholesterol oxidase]] | [[Category: Cholesterol oxidase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Streptomyces sp.]] | ||
[[Category: Brammer, L.]] | [[Category: Brammer, L.]] | ||
[[Category: Lyubimov, A Y.]] | [[Category: Lyubimov, A Y.]] | ||
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[[Category: Secreted]] | [[Category: Secreted]] | ||
[[Category: Steroid metabolism]] | [[Category: Steroid metabolism]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jun 11 10:58:24 2008'' |
Revision as of 07:58, 11 June 2008
Cholesterol oxidase from Streptomyces sp. F359W mutant (0.95A)
Overview
The usage by enzymes of specific binding pathways for gaseous substrates or products is debated. The crystal structure of the redox enzyme cholesterol oxidase, determined at sub-angstrom resolution, revealed a hydrophobic tunnel that may serve as a binding pathway for oxygen and hydrogen peroxide. This tunnel is formed by a cascade of conformational rearrangements and connects the active site with the exterior surface of the protein. To elucidate the relationship between this tunnel and gas binding and release, three mutant enzymes were constructed to block the tunnel or its putative gate. Mutation of the proposed gating residue Asn485 to Asp or tunnel residue Phe359 or Gly347 to Trp or Asn reduces the catalytic efficiency of oxidation. The K mO 2 increases from 300 +/- 35 microM for the wild-type enzyme to 617 +/- 15 microM for the F359W mutant. The k cat for the F359W mutant-catalyzed reaction decreases 13-fold relative to that of the wild-type-catalyzed reaction. The N485D and G347N mutants could not be saturated with oxygen. Transfer of hydride from the sterol to the flavin prosthetic group is no longer rate-limiting for these tunnel mutants. The steady-state kinetics of both wild-type and tunnel mutant enzymes are consistent with formation of a ternary complex of steroid and oxygen during catalysis. Furthermore, kinetic cooperativity with respect to molecular oxygen is observed with the tunnel mutants, but not with the wild-type enzyme. A rate-limiting conformational change for binding and release of oxygen and hydrogen peroxide, respectively, is consistent with the cooperative kinetics. In the atomic-resolution structure of F359W, the indole ring of the tryptophan completely fills the tunnel and is observed in only a single conformation. The size of the indole is proposed to limit conformational rearrangement of residue 359 that leads to tunnel opening in the wild-type enzyme. Overall, these results substantiate the functional importance of the tunnel for substrate binding and product release.
About this Structure
3CNJ is a Single protein structure of sequence from Bacteria. Full crystallographic information is available from OCA.
Reference
The Binding and Release of Oxygen and Hydrogen Peroxide Are Directed by a Hydrophobic Tunnel in Cholesterol Oxidase., Chen L, Lyubimov AY, Brammer L, Vrielink A, Sampson NS, Biochemistry. 2008 Apr 15;. PMID:18410129 Page seeded by OCA on Wed Jun 11 10:58:24 2008
