NH...S HYDROGEN-BONDS IN PEPTOCOCCUS-AEROGENES FERREDOXIN, CLOSTRIDIUM-PASTEURIANUM RUBREDOXIN, AND CHROMATIUM HIGH POTENTIAL IRON PROTEIN
NH...S HYDROGEN-BONDS IN PEPTOCOCCUS-AEROGENES FERREDOXIN, CLOSTRIDIUM-PASTEURIANUM RUBREDOXIN, AND CHROMATIUM HIGH POTENTIAL IRON PROTEIN
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DOI：
10.1073/pnas.72.12.4854
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发表时间：
1975-01-01
影响因子：
11.1
通讯作者：
JENSEN, LH
中科院分区：
文献类型：
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作者：
ADMAN, E;WATENPAUGH, KD;JENSEN, LH
用X射线衍射法对产气假单胞菌铁氧还蛋白和巴氏杆菌红色还蛋白晶体结构的精细化结果表明，前者有15-18个NH-S键，后者有6个，长度在3.1-3.9A之间。早期的氚交换实验与铁氧还蛋白结构中这些氢键的存在是一致的，并表明脱铁还蛋白中可用于交换的多肽氢原子比完整铁还蛋白中的多。观察到四种类型的NH-S键，其中两种与3(10)NH-O键在几何上相似。铁氧还蛋白中NH-S键的存在比高势铁蛋白中的NH-S键多，这说明了为什么铁还蛋白中Fe4S4簇的-2形式比高势铁蛋白中的-1形式更受欢迎。通过比较Rubredox、Ferredosin和高势铁蛋白中的Cys-X-Y-Cys序列，我们认为需要两个Cys-X-Y-Cys-Z序列来形成一个铁簇，不需要超过一个Cys-X-Y-Cys-Z-Gly序列来形成Fe2S2铁还蛋白，以及一个Cys-X-Y-Cys-Gly序列，其中Y具有这样的构象，使得半胱氨酸与不同的铁原子成键是形成四聚体簇所必需的。
Results from refinement of the crystal structures of P. aerogenes ferredoxin and C. pasteurianum rubredoxin determined by x-ray diffraction show that there are 15-18 NH---S bonds in the former and six in the latter with lengths in the range 3.1-3.9 A. Earlier tritium exchange experiments are consistent with the presence of these hydrogen bonds in the ferredoxin structure and show that more peptide hydrogen atoms are available for exchange in apoferredoxin than in intact ferredoxin. Four types of NH---S bonds are observed and two of these are geometrically similar to the two types of 3(10) NH---O bonds. The existence of more NH---S bonds in ferredoxin than in high potential iron protein suggests why the -2 form of the Fe4S4 cluster is preferred in ferredoxin over the -1 form found in high potential iron protein. From comparison of Cys-X-Y-Cys sequences in rubredoxin, ferredoxin, and high potential iron protein we suggest that two Cys-X-Y-Cys-Z sequences, where Z may have conformation angles similar to glycine, are required to make a one-iron cluster, no more than one Cys-X-Y-Cys-Z-Gly sequence is required to form a Fe2S2 ferredoxin, and a Cys-X-Y-Cys-Gly sequence where Y has a conformation such that the cysteines bond to different iron atoms is necessary to form the tetrameric cluster.