STRUCTURE OF ACTIVATED ACONITASE - FORMATION OF THE [4FE-4S] CLUSTER IN THE CRYSTAL
STRUCTURE OF ACTIVATED ACONITASE - FORMATION OF THE [4FE-4S] CLUSTER IN THE CRYSTAL
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DOI：
10.1073/pnas.86.10.3639
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发表时间：
1989-05-01
影响因子：
11.1
通讯作者：
STOUT, CD
中科院分区：
文献类型：
--
作者：
ROBBINS, AH;STOUT, CD
含有[4Fe-4S]簇的活化猪心乌头酸酶[柠檬酸（异柠檬酸）水解酶，EC 4.2.1.3]的结构已在2.5-.分离度为18.2%的晶体学残留。该结构与最近测定的2.1-ANG的比较。通过差分傅立叶分析，含有[3Fe-4S]簇的失活酶的解析结构表明，在活化时，铁被同晶地插入到结构中。[3Fe-4S]和[4Fe-4S]核的共同原子在0.1 α NG内一致;三个共同的半胱氨酰S γ配体原子在0.25埃内一致。插入到[3Fe-4S]簇中的Fe的第四配体是来自溶剂的水或羟基，这与酶活性位点裂缝中不存在游离半胱氨酸配体以及两种结构的同晶性一致。水分子在失活酶的晶体结构中占据类似的位置。
The structure of activated pig heart aconitase [citrate(isocitrate) hydro-lyase, EC 4.2.1.3] containing a [4Fe-4S] cluster has been refined at 2.5-.ANG. resolution to a crystallographic residual of 18.2%. Comparison of this structure to the recently determined 2.1-.ANG. resolution structure of the inactive enzyme containing a [3Fe-4S] cluster, by difference Fourier analysis, shows that upon activation iron is inserted into the structure isomorphously. The common atoms of the [3Fe-4S] and [4Fe-4S] cores agree within 0.1 .ALPHA.NG; the three common cysteinyl S.gamma. ligand atoms agree within 0.25 .ANG.. The fourth ligand of the Fe inserted into the [3Fe-4S] cluster is a water or hydroxyl from solvent, consistent with the absence of a free cysteine ligand in the enzyme active site cleft and the isomorphism of the two structures. A water molecule occupies a similar site in the crystal structure of the inactive enzyme.