ASSIGNMENT OF HEME-C RESONANCES IN 360 MHZ H-1 NMR-SPECTRA OF CYTOCHROME-C
ASSIGNMENT OF HEME-C RESONANCES IN 360 MHZ H-1 NMR-SPECTRA OF CYTOCHROME-C
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DOI：
10.1016/0005-2795(78)90564-0
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发表时间：
1978-01-01
期刊：
影响因子：
--
通讯作者：
WUTHRICH, K
中科院分区：
文献类型：
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作者：
KELLER, RM;WUTHRICH, K
在360 MHz的1H NMR谱的马心铁细胞色素c记录后，适当的数字分辨率增强，除了那些的丙酸侧链的所有血红素c质子的共振观察以及解决线。从自旋退耦和Homestrant双共振实验中的核Overhauser效应，所有这些共振被分配到它们在血红素c中的各自位置。在部分还原的细胞色素c溶液中进行饱和转移实验，进一步对铁细胞色素c中的6个血红素c甲基共振进行了归属。本实验对血红素C环甲基和meso质子共振的早期鉴定增加了个别归属，并表明硫醚桥甲基共振的早期鉴定必须修正。这些数据提供了一个基础，更详细的描述血红素c的电子结构和它的可能的关系与电子转移进出细胞色素c分子的途径。硫醚桥甲基共振的赝接触位移可能与低温下铁细胞色素c单晶中EPR测量的电子g张量有关。从这一点，现在将是可能的，没有化学修饰的蛋白质，详细比较溶液构象附近的血红素c还原和氧化的细胞色素c，从而有希望获得额外的见解，这种蛋白质的生物氧化还原反应的机制。
In the 360 MHz 1H NMR spectra of horse heart ferrocytochrome c recorded after suitable digital resolution enhancement, the resonances of all the heme c protons with the exception of those of the proprionic acid side chains were observed as well resolved lines. From spin decoupling and nuclear Overhauser effects in homonuclear double resonance experiments, all these resonances were assigned to their respective positions in heme c. With saturation transfer experiments in solutions of partially reduced cytochrome c, individual assignments were further obtained for the 6 heme c methyl resonances in ferricytochrome c. The present experiments add individual assignments to the earlier identifications of the heme c ring methyl and meso-proton resonances, and show that the earlier identificaitons of the thioether bridge methyl resonances must be revised. These data provide a basis for more detailed descriptions of the electronic structure of heme c and its possible relations with the pathway of the electron transfer in and out of the cytochrome c molecule. The pseudocontact shifts of the thioether bridge methyl resonances could be related to the electronic g-tensor measured by EPR in ferricytochrome c single crystals at low temperature. From this is will now be possible without chemical modification of the protein, to compare in detail the solution conformations near the heme c in reduced and oxidized cytochrome c and thus hopefully to obtain additional insights into the mechanism of the biological redox reaction of this protein.