Stout C D
Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, California 92037.
J Biol Chem. 1988 Jul 5;263(19):9256-60. doi: 10.2210/pdb3fd1/pdb.
The crystal structure of the 7Fe ferredoxin from Azotobacter vinelandii has been redetermined using area detector data to 2.7-A resolution and a new derivative. Tetragonal crystals of the protein were maintained at pH 8.0. The results show that the structure previously reported was in error and confirms a recent independent report of the structure (Stout, G.H., Turley, S., Sieker, L. C., and Jensen, L. H. (1988) Proc. Natl. Acad. Sci. U. S. A. 85, in press). The protein fold is similar to the homologous 8Fe ferredoxin structure for the N-terminal half of the protein; the C-terminal residues wrap around this structure. The structure contains a 3Fe cluster coordinated by cysteines 8, 16, and 49 and a 4Fe cluster coordinated by cysteines 20, 39, 42, and 45. However, there are two free sulfhydryls, cysteines 11 and 24, in the new model. Cysteine 24 is in contact with the [4Fe-4S] cluster. Cysteine 11 is shielded from solvent by residues 86-90.
利用面积探测器数据和一种新的衍生物，对来自棕色固氮菌的7Fe铁氧化还原蛋白的晶体结构进行了重新测定，分辨率达到2.7埃。该蛋白质的四方晶体在pH 8.0条件下保存。结果表明，先前报道的结构有误，并证实了最近一篇关于该结构的独立报道（斯托特，G.H.，特利，S.，西克，L.C.，和詹森，L.H.（1988年）《美国国家科学院院刊》85卷，即将发表）。该蛋白质的折叠结构与同源8Fe铁氧化还原蛋白N端一半的结构相似；C端残基围绕此结构。该结构包含一个由半胱氨酸8、16和49配位的3Fe簇以及一个由半胱氨酸20、39、42和45配位的4Fe簇。然而，在新模型中有两个游离巯基，即半胱氨酸11和24。半胱氨酸24与[4Fe-4S]簇接触。半胱氨酸11被86 - 90位残基屏蔽于溶剂之外。
