Reactions of Synthetic [2Fe-2S] and [4Fe-4S] Clusters with Nitric Oxide and Nitrosothiols
Reactions of Synthetic [2Fe-2S] and [4Fe-4S] Clusters with Nitric Oxide and Nitrosothiols
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DOI：
10.1021/ja8054996
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发表时间：
2008-11-19
影响因子：
15
通讯作者：
Lippard, Stephen J.
中科院分区：
文献类型：
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作者：
Harrop, Todd C.;Tonzetich, Zachary J.;Lippard, Stephen J.
一氧化氮（NO）与铁硫簇蛋白的相互作用导致铁硫簇蛋白的降解和分解，产生二亚硝酰铁络合物（DNIC）。在某些情况下，从这样的簇系统形成DNIC可以导致调节途径的激活或酶活性的丧失。为了理解这些过程的基本化学，我们研究了NO与合成的[2Fe-2S]和[4Fe-4S]簇合物的反应。过量的NO（g）与[Fe 2S 2（SR）（4）]（2-）（R = Ph、对甲苯基（4-MeC 6 H4）或1/2（CH 2）（2）-o-C6 H4）的溶液反应干净地得到相应的DNIC，[Fe（NO）（2）（SR）（2）]（-），伴随着作为元素硫的桥接硫化物配体的还原消除。通过X射线衍射分析证实了（Et 4 N）[Fe（NO）（2）（S-P-tolyl）（2）]的结构。[4Fe-4S]簇合物[Fe 4S 4（SR）（4）]（2-）（R = Ph，CH 2 Ph，Bu-t，或1/2（CH 2）-m-C6 H4）在没有添加硫醇盐的情况下进行反应，产生黑曲霉素黑盐[Fe 4S 3（NO）（7）]（-）。相反，（Et 4 N）（2）[Fe 4S 4（SPh）（4）]在4当量（Et 4 N）（SPh）存在下与NO（g）反应，得到预期的DNIC。对于所有反应，我们可以使用三苯甲基-S-亚硝基硫醇（Ph 3CSNO）作为一氧化氮源再现NO（g）影响的化学。这些结果证明了生物系统中铁硫簇与一氧化氮反应的可能途径，并强调了硫醇盐与铁的比例在稳定DNIC中的重要性。
The interaction of nitric oxide (NO) with iron-sulfur cluster proteins results in degradation and breakdown of the cluster to generate dinitrosyl iron complexes (DNICs). In some cases the formation of DNICs from such cluster systems can lead to activation of a regulatory pathway or the loss of enzyme activity. In order to understand the basic chemistry underlying these processes, we have investigated the reactions of NO with synthetic [2Fe-2S] and [4Fe-4S] clusters. Reaction of excess NO(g) with solutions of [Fe2S2(SR)(4)](2-) (R = Ph, p-tolyl (4-MeC6H4), or 1/2 (CH2)(2)-o-C6H4) cleanly affords the respective DNIC, [Fe(NO)(2)(SR)(2)](-), with concomitant reductive elimination of the bridging sulfide ligands as elemental sulfur. The structure of (Et4N)[Fe(NO)(2)(S-P-tolyl)(2)] was verified by X-ray crystallography. Reactions of the [4Fe-4S] clusters, [Fe4S4(SR)(4)](2-) (R = Ph, CH2Ph, Bu-t, or 1/2 (CH2)-m-C6H4) proceed in the absence of added thiolate to yield Roussin's black salt, [Fe4S3(NO)(7)](-). In contrast, (Et4N)(2)[Fe4S4(SPh)(4)] reacts with NO(g) in the presence of 4 equiv of (Et4N)(SPh) to yield the expected DNIC. For all reactions, we could reproduce the chemistry effected by NO(g) with the use of trityl-S-nitrosothiol (Ph3CSNO) as the nitric oxide source. These results demonstrate possible pathways for the reaction of iron-sulfur clusters with nitric oxide in biological systems and highlight the importance of thiolate-to-iron ratios in stabilizing DNICs.