Jean Jeener NMR Centre, Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium.
J Biomol NMR. 2013 Jul;56(3):255-63. doi: 10.1007/s10858-013-9744-8. Epub 2013 May 25.
Here we present a solution NMR study of the complex between yeast cytochrome c (Cc) and cytochrome c peroxidase (CcP), a paradigm for understanding the biological electron transfer. Performed for the first time, the CcP-observed heteronuclear NMR experiments were used to probe the Cc binding in solution. Combining the Cc- and CcP-detected experiments, the binding interface on both proteins was mapped out, confirming that the X-ray structure of the complex is maintained in solution. Using NMR titrations and chemical shift perturbation analysis, we show that the interaction is independent of the CcP spin-state and is only weakly affected by the Cc redox state. Based on these findings, we argue that the complex of the ferrous Cc and the cyanide-bound CcP is a good mimic of the catalytically-active Cc-CcP compound I species. Finally, no chemical shift perturbations due to the Cc binding at the low-affinity CcP site were observed at low ionic strength. We discuss possible reasons for the absence of the effects and outline future research directions.
在这里，我们呈现了一个关于酵母细胞色素 c（Cc）与细胞色素 c 过氧化物酶（CcP）复合物的溶液 NMR 研究，这是理解生物电子转移的范例。首次进行的 CcP 观察到的异核 NMR 实验用于探测溶液中的 Cc 结合。结合 Cc 和 CcP 检测实验，我们绘制出了两个蛋白质的结合界面，证实了该复合物在溶液中的 X 射线结构得以维持。通过 NMR 滴定和化学位移扰动分析，我们表明该相互作用不依赖于 CcP 的自旋态，并且仅受 Cc 氧化还原状态的微弱影响。基于这些发现，我们认为亚铁 Cc 和氰化物结合的 CcP 的复合物是催化活性 Cc-CcP 化合物 I 物种的良好模拟物。最后，在低离子强度下，在低亲和力 CcP 位点处由于 Cc 结合而没有观察到化学位移扰动。我们讨论了不存在这些影响的可能原因，并概述了未来的研究方向。
