Guiard B, Lederer F
Biochim Biophys Acta. 1978 Sep 26;536(1):88-96. doi: 10.1016/0005-2795(78)90054-5.
From previous work (Guiard, B., Groudinsky, O. and Lederer, F. (1974) Proc. Natl. Acad. Sci. U.S. 71, 2539-2543) it is now clear that the overall secondary and tertiary structure of cytochrome b2 core is very similar to that of cytochrome b5. We present here a direct comparison of circular dichroism spectra and low-temperature absorption spectra which bring further evidence about this structural similarity. Cytochrome b2 core reacts only sluggishly with cytochrome b5 reductase, showing a lack of correspondence with the reductase binding area in cytochrome b5. On the other hand, literature data indicate similar electron transfer rates between cytochrome c on one hand, cytochrome b5 and cytochrome b2 core on the other hand. A structural inspection of cytochrome b2 core suggests that the mouth of the heme crevice in the latter is the most likely region for interaction with cytochrome c, with perhaps ionic bonds slightly different from those proposed by Salemme (Salemme, F.R. (1976) J. Mol. Biol. 102, 563--568) for the cytochrome c-cytochrome b5 interaction. In view of this partial surface similarity, the lack of immunological cross-reactivity between the two hemoprotein cores is attributed to their close similarity with the cytochrome b5 of the antibody-producing rabbit.
从先前的研究工作（Guiard, B., Groudinsky, O. 和 Lederer, F. (1974) Proc. Natl. Acad. Sci. U.S. 71, 2539 - 2543）可知，细胞色素b2核心的整体二级和三级结构与细胞色素b5非常相似。我们在此展示圆二色光谱和低温吸收光谱的直接比较，这为这种结构相似性提供了进一步的证据。细胞色素b2核心与细胞色素b5还原酶的反应很缓慢，这表明它与细胞色素b5中的还原酶结合区域不对应。另一方面，文献数据表明，一方面细胞色素c与细胞色素b5和细胞色素b2核心之间的电子转移速率相似。对细胞色素b2核心的结构检查表明，后者血红素裂隙的开口是与细胞色素c相互作用最可能的区域，其离子键可能与Salemme（Salemme, F.R. (1976) J. Mol. Biol. 102, 563 - 568）提出的细胞色素c - 细胞色素b5相互作用的离子键略有不同。鉴于这种部分表面相似性，两种血红素蛋白核心之间缺乏免疫交叉反应性归因于它们与产生抗体的兔子的细胞色素b5非常相似。
