This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.

Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.


1qlu

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 1: Line 1:
-
[[Image:1qlu.jpg|left|200px]]
+
{{Seed}}
 +
[[Image:1qlu.png|left|200px]]
<!--
<!--
Line 9: Line 10:
{{STRUCTURE_1qlu| PDB=1qlu | SCENE= }}
{{STRUCTURE_1qlu| PDB=1qlu | SCENE= }}
-
'''STRUCTURE OF THE H422A MUTANT VANILLYL-ALCOHOL OXIDASE IN COMPLEX WITH ISOEUGENOL'''
+
===STRUCTURE OF THE H422A MUTANT VANILLYL-ALCOHOL OXIDASE IN COMPLEX WITH ISOEUGENOL===
-
==Overview==
+
<!--
-
By mutating the target residue of covalent flavinylation in vanillyl-alcohol oxidase, the functional role of the histidyl-FAD bond was studied. Three His(422) mutants (H422A, H422T, and H422C) were purified, which all contained tightly but noncovalently bound FAD. Steady state kinetics revealed that the mutants have retained enzyme activity, although the turnover rates have decreased by 1 order of magnitude. Stopped-flow analysis showed that the H422A mutant is still able to form a stable binary complex of reduced enzyme and a quinone methide product intermediate, a crucial step during vanillyl-alcohol oxidase-mediated catalysis. The only significant change in the catalytic cycle of the H422A mutant is a marked decrease in reduction rate. Redox potentials of both wild type and H422A vanillyl-alcohol oxidase have been determined. During reduction of H422A, a large portion of the neutral flavin semiquinone is observed. Using suitable reference dyes, the redox potentials for the two one-electron couples have been determined: -17 and -113 mV. Reduction of wild type enzyme did not result in any formation of flavin semiquinone and revealed a remarkably high redox potential of +55 mV. The marked decrease in redox potential caused by the missing covalent histidyl-FAD bond is reflected in the reduced rate of substrate-mediated flavin reduction limiting the turnover rate. Elucidation of the crystal structure of the H422A mutant established that deletion of the histidyl-FAD bond did not result in any significant structural changes. These results clearly indicate that covalent interaction of the isoalloxazine ring with the protein moiety can markedly increase the redox potential of the flavin cofactor, thereby facilitating redox catalysis. Thus, formation of a histidyl-FAD bond in specific flavoenzymes might have evolved as a way to contribute to the enhancement of their oxidative power.
+
The line below this paragraph, {{ABSTRACT_PUBMED_10585424}}, adds the Publication Abstract to the page
 +
(as it appears on PubMed at http://www.pubmed.gov), where 10585424 is the PubMed ID number.
 +
-->
 +
{{ABSTRACT_PUBMED_10585424}}
==About this Structure==
==About this Structure==
Line 31: Line 35:
[[Category: Oxidoreductase]]
[[Category: Oxidoreductase]]
[[Category: Peroxisome]]
[[Category: Peroxisome]]
-
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 06:25:42 2008''
+
 
 +
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 06:20:31 2008''

Revision as of 03:20, 29 July 2008

Image:1qlu.png

Template:STRUCTURE 1qlu

STRUCTURE OF THE H422A MUTANT VANILLYL-ALCOHOL OXIDASE IN COMPLEX WITH ISOEUGENOL

Template:ABSTRACT PUBMED 10585424

About this Structure

1QLU is a Single protein structure of sequence from Penicillium simplicissimum. Full crystallographic information is available from OCA.

Reference

Covalent flavinylation is essential for efficient redox catalysis in vanillyl-alcohol oxidase., Fraaije MW, van den Heuvel RH, van Berkel WJ, Mattevi A, J Biol Chem. 1999 Dec 10;274(50):35514-20. PMID:10585424

Page seeded by OCA on Tue Jul 29 06:20:31 2008

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/1qlu"
Personal tools