Synthetic analogues of the active site of the A-cluster of acetyl coenzyme A synthase/CO dehydrogenase: Syntheses, structures, and reactions with CO
Synthetic analogues of the active site of the A-cluster of acetyl coenzyme A synthase/CO dehydrogenase: Syntheses, structures, and reactions with CO
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DOI：
10.1021/ic0520465
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发表时间：
2006-04-17
影响因子：
4.6
通讯作者：
Mascharak, PK
中科院分区：
文献类型：
--
作者：
Harrop, TC;Olmstead, MM;Mascharak, PK
两种金属配体，即（Et 4 N）（2）[Ni（NpPepS）]（1）和（Et 4 N）（2）[Ni（PhPepS）]（2），含有作为供体的羧酰胺-N和硫醇合-S，已被用于模拟乙酰辅酶A合酶/CO脱氢酶的A簇的NDM-p-Ni-d亚位点。合成了一系列硫桥联的Ni/Cu双核和三核配合物（3-10），研究了它们的氧化还原性质和金属中心对CO的亲合性，并对（Et 4 N）（2）[Ni（PhPepS）]（2），（Et 4 N）[Cu（neo）Ni（NpPepS）]（.）0.5Et（2）O（.）0.5H（2）O（3（.）0.5Et（2）O（.）0.5H（2）O），（Et4N）[Cu-（neo）Ni（PhPepS）]（H2O）-H-.（4（.）H（2）O），（Et4N）（2）[Ni{Ni（NpPepS）}2]（DMF）-D-。（5-DMF）（Et4N）（2）[Ni（DMF）（2）{Ni（NpPepS）}（2）]（DMF）-D-。（6-31）DMF）、（Et4N）（2）[Ni（DMF）（2）{Ni（PhPepS）}2]（8）和[Ni（dppe）Ni（PhPepS）]（CH2Cl2）-C-。（10-CH_2Cl_2）的晶体结构。Ni-d模拟物1和2抵抗还原并且对CO不表现出亲和力。相反，三核模型5-8中的硫桥连Ni中心（指定为Ni-C）易于还原并且以Ni（I）状态结合CO。此外，硫桥连的Nic中心可以通过用1，10-菲咯啉处理从三聚体（5-8）中除去，这很像酶中的“不稳定Ni”。双核Ni-Ni模型9和10更接近于A团簇的Ni-p-Ni-d亚位，只有二聚体的模型化Nip位可以还原。Ni（I）-Ni（II）物种分别显示了9（红色）和10（红色）的畸变三角双锥和畸变四面体几何构型的Ni（I）中心的典型EPR谱。这两个物种都与CO结合，CO加合物9（红色）-CO和10（红色）-CO分别在2044和1997 cm（-1）处显示出强的nu（co）。减少10是可逆的。还原态的10的CO-亲和力和10（red）-CO的nu（co）值与CO结合的还原A-团簇非常相似（v（co）（=）1996 cm（-1））。
Two metallosynthons, namely (Et4N)(2)[Ni(NpPepS)] (1) and (Et4N)(2)[Ni(PhPepS)] (2) containing carboxamido-N and thiolato-S as donors have been used to model the bimetallic M-p-Ni-d subsite of the A-cluster of the enzyme acetyl coenzyme A synthase/CO dehydrogenase. A series of sulfur-bridged Ni/Cu dinuclear and trinuclear complexes (3-10) have been synthesized to explore their redox properties and affinity of the metal centers toward CO. The structures of (Et4N)(2)[Ni(PhPepS)] (2), (Et4N)[Cu(neo)Ni(NpPepS)](.)0.5Et(2)O(.)0.5H(2)O (3(.)0.5Et(2)O(.)0.5H(2)O), (Et4N)[Cu-(neo)Ni(PhPepS)](H2O)-H-. (4(.)H(2)O), (Et4N)(2)[Ni{Ni(NpPepS)}2](DMF)-D-. (5-DMF) (Et4N)(2)[Ni(DMF)(2){Ni(NpPepS)}(2)](DMF)-D-. (6-31)DMF), (Et4N)(2)[Ni(DMF)(2){Ni(PhPepS)}2](8), and [Ni(dppe)Ni(PhPepS)](CH2Cl2)-C-. (10-CH2Cl2) have been determined by crystallography. The Ni-d mimics 1 and 2 resist reduction and exhibit no affinity toward CO. In contrast, the sulfur-bridged Ni center (designated Ni-C) in the trinuclear models 5-8 are amenable to reduction and binds CO in the Ni(l) state. Also, the sulfur-bridged Nic center can be removed from the trimers (5-8) by treatment with 1,10-phenanthroline much like the "labile Ni" from the enzyme. The dinuclear Ni-Ni models 9 and 10 resemble the Ni-p-Ni-d subsite of the A-cluster more closely, and only the modeled Nip site of the dimers can be reduced. The Ni(l)-Ni(II) species display EPR spectra typical of a Ni(l) center in distorted trigonal bipyramidal and distorted tetrahedral geometries for 9(red) and 10(red), respectively. Both species bind CO, and the CO-adducts 9(red)-CO and 10(red)-CO display strong nu(co) at 2044 and 1997 cm(-1), respectively. The reduction of 10 is reversible. The CO-affinity of 10 in the reduced state and the nu(co) value of 10(red)-CO closely resemble the CO-bound reduced A-cluster (v(co) (=) 1996 cm(-1)).