Fourier‐transform infrared studies on azide‐binding to the binuclear center of the Escherichia coli bo‐type ubiquinol oxidase 1

FEBS Letters

Mogi, Tatsushi¹  Hori, Hiroshi²  Tsubaki, Motonari³ 

[1] Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;Division of Biophysical Engineering, Graduate School of Engineering Science, Osaka University, Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan;Department of Life Science, Faculty of Science, Himeji Institute of Technology, Kamigoori-cho, Akou-gun, Hyogo 678-1297, Japan

关键词: Escherichia coli bo-type ubiquinol oxidase;    Fourier-transform infrared;    Heme-copper binuclear center;    Azide;    Isotope label;    Bridging structure;   

DOI  :  10.1016/S0014-5793(99)00423-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Azide-binding to the heme-copper binuclear center of bo-type ubiquinol oxidase from Escherichia coli was investigated with Fourier-transform infrared spectroscopy. Deconvolution analyses of infrared spectra of the azide (¹⁴N₃)-inhibited air-oxidized form showed a major infrared azide antisymmetric stretching band at 2041 cm⁻¹. An additional band developed at 2062.5 cm⁻¹ during a longer incubation. Isotope substitutions with terminally ¹⁵N-labelled azides did not show a splitting of the major band, indicating that the geometry of the bound azide is mainly in a bridging configuration between high-spin heme o and Cu_B. The band at 2062.5 cm⁻¹ showed clear splittings upon substitution with the terminally ¹⁵N-labelled azides, indicating the Cu_B ²⁺-N=N=N structure. Partial reduction of the oxidase with β-NADH in the presence of azide caused an appearance of new infrared bands at 2038.5 (major) and 2009 (minor) cm⁻¹. The former band also showed clear splittings in the presence of the terminally ¹⁵N-labelled azides, indicating that reduction of low-spin heme b alters the structure of the binuclear center leading to the Fe_o ³⁺-N=N=N configuration.

【 授权许可】

Unknown