TY - JOUR
T1 - (μ-1,2-peroxo)diiron(III/IIl) complex as a precursor to the diiron(III/IV) intermediate X in the assembly of the iron-radical cofactor of ribonucleotide reductase from mouse
AU - Yun, Danny
AU - García-Serres, Ricardo
AU - Chicalese, Brandon M.
AU - An, Young H.
AU - Huynh, Boi Hanh
AU - Bollinger, J. Martin
PY - 2007/2/20
Y1 - 2007/2/20
N2 - Stopped-flow absorption and freeze-quench electron paramagnetic resonance (EPR) and Mössbauer spectroscopies have been used to obtain evidence for the intermediacy of a (μ-1,2-peroxo)-diiron(III/III) complex on the pathway to the tyrosyl radical and (μ-oxo)diiron(III/III) cluster during assembly of the essential cofactor in the R2 subunit of ribonucleotide reductase from mouse. The complex accumulates to ∼0.4 equiv in the first few milliseconds of the reaction and decays concomitantly with accumulation of the previously detected diiron(III/IV) cluster, X, which generates the tyrosyl radical and product (μ-oxo)diiron(III/III) cluster. Kinetic complexities in the reaction suggest the existence of an anti-cooperative interaction of the monomers of the R2 homodimer in Fe(II) binding and perhaps O2 activation. The detection of the (μ-1,2-peroxo)diiron(III/III) complex, which has spectroscopic properties similar to those of complexes previously characterized in the reactions of soluble methane monooxygenase, stearoyl acyl carrier protein Δ9 desaturase, and variants of Escherichia coli R2 with the iron ligand substitution, D84E, provides support for the hypothesis that the reactions of the diiron-carboxylate oxidases and oxygenases commence with the formation of this common intermediate.
AB - Stopped-flow absorption and freeze-quench electron paramagnetic resonance (EPR) and Mössbauer spectroscopies have been used to obtain evidence for the intermediacy of a (μ-1,2-peroxo)-diiron(III/III) complex on the pathway to the tyrosyl radical and (μ-oxo)diiron(III/III) cluster during assembly of the essential cofactor in the R2 subunit of ribonucleotide reductase from mouse. The complex accumulates to ∼0.4 equiv in the first few milliseconds of the reaction and decays concomitantly with accumulation of the previously detected diiron(III/IV) cluster, X, which generates the tyrosyl radical and product (μ-oxo)diiron(III/III) cluster. Kinetic complexities in the reaction suggest the existence of an anti-cooperative interaction of the monomers of the R2 homodimer in Fe(II) binding and perhaps O2 activation. The detection of the (μ-1,2-peroxo)diiron(III/III) complex, which has spectroscopic properties similar to those of complexes previously characterized in the reactions of soluble methane monooxygenase, stearoyl acyl carrier protein Δ9 desaturase, and variants of Escherichia coli R2 with the iron ligand substitution, D84E, provides support for the hypothesis that the reactions of the diiron-carboxylate oxidases and oxygenases commence with the formation of this common intermediate.
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U2 - 10.1021/bi061717n
DO - 10.1021/bi061717n
M3 - Article
C2 - 17256972
AN - SCOPUS:33847058857
VL - 46
SP - 1925
EP - 1932
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 7
ER -