NDLI: Heme Iron Nitrosyl Complex of MauG Reveals an Efficient Redox Equilibrium Between Hemes with Only One Heme Exclusively Binding Exogenous Ligands

Content Provider	PubMed Central
Author	Fu, Rong Liu, Fange Davidson, Victor L. Liu, Aimin
Abstract	MauG is a diheme enzyme that oxidizes two protein-bound tryptophan residues to generate a catalytic tryptophan tryptophylquinone cofactor within methylamine dehydrogenase. Upon the two-electron oxidation of bis-ferric MauG, the two c-type hemes exist as a spin-uncoupled bis-Fe(IV) species with only one binding oxygen, which is chemically equivalent to a single ferryl heme plus a π porphyrin cation radical (Li, X. et al. (2008) Proc. Natl. Acad. Sci. U.S.A. 105, 8597–8600). The EPR spectrum of the nitrosyl complex of fully reduced MauG shows a single six-coordinate Fe(II)-NO species, which is characteristic of a histidine-ligated Fe(II)-NO moiety in the heme environment. Exposure of partially reduced MauG to NO reveals a redox equilibrium with facile electron transfer between hemes, but with only one binding nitric oxide. Thus, the second heme is able to stabilize all three redox states of iron (Fe(II), Fe(III) and Fe(IV)) in a six-coordinate protein-bound heme without binding exogenous ligands. This is unprecedented behavior for a protein-bound heme for which each of these redox states is relevant to the overall catalytic mechanism. The results also illustrate the electronic communication between the two iron centers which function as a diheme unit rather than independent heme cofactors.
Related Links	http://dx.doi.org/10.1021/bi9017544
Ending Page	11605
Page Count	3
Starting Page	11603
File Format	PDF
ISSN	00062960
e-ISSN	15204995
Journal	Biochemistry
Issue Number	49
Volume Number	48
Language	English
Publisher Date	2009-12-15
Access Restriction	Open
Subject Keyword	Biochemistry Research in Higher Education
Content Type	Text
Resource Type	Article
Subject	Biochemistry

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Evidence for Redox Cooperativity between c-Type Hemes of MauG which is Likely Coupled to Oxygen Activation during Tryptophan Tryptophylquinone Biosynthesis

Isocyanide or nitrosyl complexation to hemes with varying tethered axial base ligand donors: synthesis and characterization

Tuning of Hemes b Equilibrium Redox Potential Is Not Required for Cross-Membrane Electron Transfer

Long Range Electron Transfer Reactions between Hemes of MauG and Different Forms of Tryptophan Tryptophylquinone of Methylamine Dehydrogenase

Geometric and electronic structures of the His–Fe(IV)=O and His–Fe(IV)–Tyr hemes of MauG

Electron paramagnetic resonance studies of nitrosyl ferrous heme complexes. Determination of an equilibrium between two conformations.

Construction of a bisaquo heme enzyme and binding by exogenous ligands.

Anisotropic Iron Motion in Nitrosyl Iron Porphyrinates:Natural and Synthetic Hemes

Spectral transitions of nitrosyl hemes during ligand binding to hemoglobin.

Heme Iron Nitrosyl Complex of MauG Reveals an Efficient Redox Equilibrium Between Hemes with Only One Heme Exclusively Binding Exogenous Ligands

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Evidence for Redox Cooperativity between c-Type Hemes of MauG which is Likely Coupled to Oxygen Activation during Tryptophan Tryptophylquinone Biosynthesis

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Heme Iron Nitrosyl Complex of MauG Reveals an Efficient Redox Equilibrium Between Hemes with Only One Heme Exclusively Binding Exogenous Ligands