Synthesis, spectroscopic and X-ray characterization of various pyrazine-bridged platinum(II) complexes: 1H NMR comparative study of their catalytic abilities in the hydrolysis of methionine- and histidine-containing dipeptides
Synthesis, spectroscopic and X-ray characterization of various pyrazine-bridged platinum(II) complexes: 1H NMR comparative study of their catalytic abilities in the hydrolysis of methionine- and histidine-containing dipeptides
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各种吡嗪桥铂(II)络合物的合成、光谱和X射线表征：1H NMR比较研究它们在含蛋氨酸和组氨酸二肽水解中的催化能力
DOI：
10.1016/j.poly.2016.06.011
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
M. Djuran
中科院分区：
文献类型：
--
作者：
S. Rajković;Marija D. Živković;B. Warżajtis;U. Rychlewska;M. Djuran
四个吡嗪桥联铂配合物[{Pt（1，3-Pd）Cl}2（μ-pz）] Cl 2·LiCl（1）（1，3-pd = 1，3-丙二胺），[{Pt（2，2-diMe-1，3-pd）Cl}2（μ-pz）]Cl2·2[Li（H2O）4]Cl·2H2O（2）（2，2-diMe-1，3-pd = 2，2-二甲基-1，3-丙二胺），[{Pt（1，3-pnd）Cl}2（μ-pz）]（ClO 4）2·H2O（3）合成了（1，3-pnd =（±）-1，3-戊二胺）和[{Pt（1，3-pnd）Cl}2（μ-pz）] Cl 2·2[Pt（1，3-pnd）Cl 2]·2 H2O（4）。对化合物1 -3进行了NMR和UV-Vis光谱表征，对配合物2和4进行了单晶X-射线分析。4晶体中的原子分布显示出无序性，这可能是由于[{Pt（1，3-pnd）Cl}2（μ-pz）]2+络合阳离子的四种不同立体异构体在同一晶体学位置上的存在。通过~（13）C核磁共振谱，在配合物3中还观察到了四种立体异构体的存在。配合物1 - 3转化为相应的水溶性配合物[{Pt（X）（H_2O）}_2（μ-pz）]_4 ~+（X分别为1，3-Pd、2，2-diMe-1，3-Pd和1，3-pnd），用核磁共振氢谱（1HNMR）和核磁共振氢谱（1HNMR）比较了它们与类似的单核[Pt（X）（H2O）2]2+和吡嗪桥联[{Pt（en）（H2O）}2（μ-pz）]4+的催化活性在N-乙酰化的1-甲硫氨酰甘氨酸（Ac-l-Met-Gly）和1-组氨酰甘氨酸（Ac-l-His-Gly）的水解中的络合物。所有反应均在37 °C下在pH 2.0-2.5范围内进行。结果表明，所有研究的双核Pt（II）-水配合物都促进了Ac-l-Met-Gly中锚定氨基酸甲硫氨酸或Ac-l-His-Gly中锚定氨基酸组氨酸的酰胺键的选择性断裂。（在乙二胺中为五元，在1，3-丙二胺中为六元），3-丙二胺配体对Ac-l-Met-Gly二肽的水解速率有显著影响。Ac-l-His-Gly的水解速率受这两个因素的影响，其顺序为> 1，3-pd > 1，3-pnd > 2，2-diMe-1，3-pd。此外，它已被证明，所有研究的双核铂（II）-水配合物是更好的催化剂，在水解的二肽比类似的单核铂（II）-水配合物。目前的研究结果预计将发挥至关重要的作用，在开发新的Pt（II）配合物，它可以作为有效的催化剂的选择性水解的肽含有蛋氨酸或组氨酸残基。
Four pyrazine (pz)-bridged Pt(II) complexes, [{Pt(1,3-pd)Cl}2(μ-pz)]Cl2·LiCl (1) (1,3-pd = 1,3-propylenediamine), [{Pt(2,2-diMe-1,3-pd)Cl}2(μ-pz)]Cl2·2[Li(H2O)4]Cl·2H2O (2) (2,2-diMe-1,3-pd = 2,2-dimethyl-1,3-propylenediamine), [{Pt(1,3-pnd)Cl}2(μ-pz)](ClO4)2·H2O (3) (1,3-pnd = (±)-1,3-pentanediamine) and [{Pt(1,3-pnd)Cl}2(μ-pz)]Cl2·2[Pt(1,3-pnd)Cl2]·2H2O (4) have been synthesized. NMR and UV–Vis spectroscopic characterization has been performed for compounds1–3, while single-crystal X-ray analysis has been carried out for complexes2and4. Atomic distribution in the crystals of4indicated a disorder which could be attributed to the presence at the same crystallographic site of four distinct stereoisomers of the [{Pt(1,3-pnd)Cl}2(μ-pz)]2+complex cation. The presence of four stereoisomeric products was also observed in complex3by13C NMR spectroscopy. Complexes1–3were converted into the corresponding aqua complexes, [{Pt(X)(H2O)}2(μ-pz)]4+(X is 1,3-pd, 2,2-diMe-1,3-pd and 1,3-pnd, respectively), and1H NMR spectroscopy was applied for comparison of their catalytic activities with those of the analogous mononuclear [Pt(X)(H2O)2]2+and pyrazine-bridged [{Pt(en)(H2O)}2(μ-pz)]4+complexes in the hydrolysis of theN-acetylatedl-methionylglycine (Ac-l-Met-Gly) andl-histidylglycine (Ac-l-His-Gly). All reactions were performed in the pH range 2.0–2.5 at 37 °C. It was found that all investigated dinuclear Pt(II)-aqua complexes promote selective cleavage of the amide bond involving carboxylic group of the anchoring amino acid methionine in the Ac-l-Met-Gly or histidine in the Ac-l-His-Gly.1H NMR data indicate that neither the size of the chelated diamine ring (five-membered in ethylenediamine and six-membered in 1,3-propylenediamine) nor the bulky substituents incorporated into the 1,3-propylenediamine ligand have significant influence on the rate of hydrolysis of Ac-l-Met-Gly dipeptide. Meanwhile, the rate of hydrolysis of Ac-l-His-Gly depends on both of these factors and decreases in order en > 1,3-pd > 1,3-pnd > 2,2-diMe-1,3-pd. Moreover, it has been shown that all investigated dinuclear Pt(II)-aqua complexes are better catalytic agents in the hydrolysis of the dipeptides than the analogous mononuclear Pt(II)-aqua complexes. The present findings are expected to play a crucial role in the development of new Pt(II) complexes, which can act as effective catalytic reagents for the selective hydrolysis of peptides containing either methionine or histidine residues.