Resonance Raman Detection of the Fe2+−C−N Modes in Heme−Copper Oxidases:  A Probe of the Active Site

• Published in: Inorganic chemistry Vol. 43; no. 16; pp. 4907 - 4910
• Main Authors: Pinakoulaki, Eftychia, Vamvouka, Magdalini, Varotsis, Constantinos
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 09-08-2004
• Subjects: Animals; Binding Sites; Cattle; Cyanides - chemistry; Cyanides - metabolism; Cytochromes - chemistry; Cytochromes - metabolism; Electron Transport Complex IV - chemistry; Electron Transport Complex IV - metabolism; Escherichia coli - enzymology; Escherichia coli Proteins; Heart; Heme - chemistry; Heme - metabolism; Iron - chemistry; Iron - metabolism; Models, Molecular; Oxidation-Reduction; Oxidoreductases - chemistry; Oxidoreductases - metabolism; Protein Binding; Rhodobacter sphaeroides - enzymology; Spectrum Analysis, Raman
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic035216r

Resonance Raman spectroscopy has been employed to investigate the reduced cyano complexes of cytochrome aa 3 from bovine heart and Rhodobacter sphaeroides and of cytochrome bo 3 from E. coli. In the aa 3-type oxidases, the frequency of the Fe−CN stretching mode is located at 468 cm-1, and the bending Fe−C−N vibration, at 500 cm-1. The fully reduced cytochrome bo 3−CN complex gives rise to a stretching vibration at 468 cm-1, a bending vibration at 491 cm-1, and a stretching C−N vibration at 2037 cm-1. The observed differences between aa 3 and bo 3 oxidases in the frequencies of the Fe−C−N group suggest a quantitative difference in the structure of the His−heme a 3 2+/CuB 1+ and His−heme o 3 2+/CuB 1+ binuclear pockets upon CN- binding.