Cyanide binding and active site structure in heme-copper oxidases: Normal coordinate analysis of iron-cyanide vibrations of 3.0.CO;2-A/asset/equation/tex2gif-ueqn-1.gif?v=1&t=h5l2h72t&s=02cc73955ac381d2412b32448006eaf1ff5323cf" class="inlineGraphic"> CN− complexes of cytochromes ba3 and aa3
✍ Scribed by Younkyoo Kim; Gerald T. Babcock; Kristene K. Surerus; James A. Fee; R. Brian Dyer; William H. Woodruff; W. Anthony Oertling
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 260 KB
- Volume
- 4
- Category
- Article
- ISSN
- 1075-4261
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✦ Synopsis
The cyanide isotope-sensitive low-frequency vibrations of ferrous cyano complexes of cytochrome a 3 are studied for cytochrome ba 3 from Thermus thermophilus and cytochrome aa 3 from bovine heart. Cyanide complexes of ba 3 display three isotope sensitive frequencies at 512, 485, and 473 cm 01 . The first is primarily an Fe-C stretching motion, whereas the lower wavenumber modes are bending motions. These ironcyanide vibrations are independent of the redox levels of the other metal centers in the protein. On the other hand, the fully reduced bovine derivative complexed with cyanide gives rise to a bending vibration at 503 cm 01 and a stretching vibration at 469 cm 01 . That is, the ordering of the stretching and bending frequencies is reversed from that of the bacterial protein. These results are analyzed by normal coordinate calculations to obtain comparative models for the binuclear O 2 reducing site of the two proteins. We find that the observed frequencies are consistent with a linear Fe-C-N group and larger Fe-C stretching force constant (2.558 mdyn/A ˚) for ba 3 and a slightly bent Fe-C-N group (angle Ç170Њ) and a smaller Fe-C stretching force constant (2.335 mdyn/ Correspondence to: W. A. Oertling.