Spectroscopic Evidence for a High-Spin Br-Fe(IV)-Oxo Intermediate in the -Ketoglutarate-Dependent Halogenase CytC3 from Streptomyces

详细信息    查看全文

• 作者：Danica Galoni Fujimori ; Eric W. Barr ; Megan L. Matthews ; Gretchen M. Koch ; J. Ryan Yonce ; Christopher T. Walsh ; J. Martin Bollinger ; Jr. ; Carsten Krebs ; Pamela J. Riggs-Gelasco
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：November 7, 2007
• 年：2007
• 卷：129
• 期：44
• 页码：13408 - 13409
• 全文大小：87K
• 年卷期：v.129,no.44(November 7, 2007)
• ISSN：1520-5126

文摘

The complex of the mononuclear non-heme halogenase CytC3 from Streptomyces, Fe(II), -ketoglutarate, bromide, and the substrate L-2-aminobutyryl-S-CytC2 reacts with O₂ to form a reaction intermediate. Variable-field, freeze-quench Mössbauer spectroscopy reveals this intermediate to be a mixture of two high-spin Fe(IV) complexes in an approximate 3.7/1 ratio. Freeze-quench Fe K-edge X-ray absorption spectroscopy provides further insight into the structure of this intermediate. A short 1.62-Å interaction between the Fe and one of its ligands is attributed to the Fe(IV)-oxo group, and a 2.43-Å interaction is assigned to the Fe-Br interaction. A significantly longer Fe-Br separation (2.53 Å) is observed in the reactant complex, consistent with lower valency of the Fe in the reactant complex. This intermediate is the first example for a Br-Fe(IV)-oxo complex in a protein and provides evidence for a unifying mechanism for Fe(II) and -ketoglutarate-dependent dioxygenases and halogenases.