Journal article
Factors that Affect Oxygen Activation and Coupling of the Two Redox Cycles in the Aromatization Reaction Catalyzed by NikD, an Unusual Amino Acid Oxidase
Biochemistry (Easton), v 48(40), pp 9542-9555
13 Oct 2009
PMID: 19702312
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
NikD is a flavoprotein oxidase that catalyzes the oxidation of piperideine-2-carboxylate (P2C) to picolinate in a remarkable aromatization reaction comprising two redox cycles and at least one isomerization step. Tyr258 forms part of an "aromatic cage" that surrounds the ring in picolinate and its precursors. Mutation of Tyr258 to Phe does not perturb the structure of nikD but does affect the coupling of the two redox cycles and causes a 10-fold decrease in turnover rate. Tyr258Phe catalyzes a quantitative 2-electron oxidation of P2C but only 60% of the resulting dihydropicolinate intermediate undergoes a second redox cycle to produce picolinate. The mutation does not affect product yield with an alternate substrate (3,4-dehydro-L-proline) that is aromatized in a single 2-electron oxidation step. Wild-type and mutant enzyme exhibit identical rate constants for P2C oxidation to dihydropicolinate and isomerization of a reduced enzyme•dihydropicolinate complex. The observed rates are 200- and 10-fold faster, respectively, than the mutant turnover rate. Picolinate release from Tyr258Phe is 100-fold faster than turnover. The presence of bound substrate or product is a key factor in oxygen activation by wild-type nikD, as judged by the 10- to 75-fold faster rates observed for complexes of the reduced enzyme with picolinate, benzoate or 1-cyclohexenoate, a 1-deaza P2C analog. The reduced Tyr258Phe•1-cyclohexenoate complex is 25-fold less reactive with oxygen than the wild-type complex. We postulate that mutation of Tyr258 causes subtle changes in active site dynamics that promote release of the reactive dihydropicolinate intermediate and disrupt the efficient synchronization of oxygen activation observed with wild-type nikD.
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Details
- Title
- Factors that Affect Oxygen Activation and Coupling of the Two Redox Cycles in the Aromatization Reaction Catalyzed by NikD, an Unusual Amino Acid Oxidase
- Creators
- Phaneeswara-Rao Kommoju - Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102Robert C Bruckner - Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102Patricia Ferreira - Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102Christopher J Carrell - Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110F. Scott Mathews - Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110Marilyn Schuman Jorns - Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102
- Publication Details
- Biochemistry (Easton), v 48(40), pp 9542-9555
- Publisher
- American Chemical Society; Washington, DC
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology
- Web of Science ID
- WOS:000270459100025
- Scopus ID
- 2-s2.0-70350063829
- Other Identifier
- 991014878394204721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Biochemistry & Molecular Biology