Ohnishi T, LoBrutto R, Salerno J C, Bruckner R C, Frey T G
J Biol Chem. 1982 Dec 25;257(24):14821-5.
We have studied the spatial relationship between cytochromes a and a3 by the enhancement of the spin relaxation of cytochrome a3-NO EPR signals by the paramagnetic a heme at 15 K. An Fe-Fe distance of 12-19A is estimated from the absence of dipolar broadening and from the observation of spin relaxation enhancement in the a3-NO complex. When this result is combined with resonance x-ray diffraction data reported by Blasie et al. (Blasie, J. K., Pachence, J. M., Tavormina, A., Dutton, P. L., Stamatoff, J., Eisenberger, P., and Brown, G. (1982) Biochim. Biophys. Acta 679, 188-197) and the contribution from the exchange interaction is considered, we can limit the iron-iron distance to 12-16 A and estimate the angle between the Fe-Fe vector and mitochondrial membrane normal as 30-60 degrees. We also consider the possible effects of CuA on cytochrome a3-NO.
我们通过在15K下顺磁性a血红素对细胞色素a3-NO EPR信号自旋弛豫的增强作用，研究了细胞色素a和a3之间的空间关系。根据偶极展宽的缺失以及a3-NO复合物中自旋弛豫增强的观察结果，估计Fe-Fe距离为12-19埃。当将该结果与Blasie等人报道的共振X射线衍射数据（Blasie, J. K., Pachence, J. M., Tavormina, A., Dutton, P. L., Stamatoff, J., Eisenberger, P., and Brown, G. (1982) Biochim. Biophys. Acta 679, 188-197）相结合，并考虑交换相互作用的贡献时，我们可以将铁-铁距离限制在12-16埃，并估计Fe-Fe向量与线粒体膜法线之间的角度为30-60度。我们还考虑了CuA对细胞色素a3-NO的可能影响。
