Al-Sayed Emir, Blazevic Amir, Roller Alexander, Rompel Annette
Institut für Biophysikalische Chemie, Fakultät für Chemie, Universität Wien, Althanstraße 14, 1090 Wien (Austria) http://www.bpc.univie.ac.at.
Institut für Anorganische Chemie, Fakultät für Chemie, Universität Wien, Währinger Straße 42, 1090 Wien (Austria).
Chemistry. 2015 Dec 1;21(49):17800-7. doi: 10.1002/chem.201502458. Epub 2015 Nov 3.
Four aromatic hybrid Anderson polyoxomolybdates with Fe(3+) or Mn(3+) as the central heteroatom have been synthesized by using a pre-functionalization protocol and characterized by using single-crystal X-ray diffraction, FTIR, ESI-MS, (1) H NMR spectroscopy, and elemental analysis. Structural analysis revealed the formation of (TBA)3 [FeMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]⋅3.5 ACN (TBA-FeMo6 -bzn; TBA=tetrabutylammonium, ACN=acetonitrile, bzn=TRIS-benzoic acid alkanolamide, TRISR=(HOCH2 )3 CR)), (TBA)3 [FeMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]⋅2.5 ACN (TBA-FeMo6 -cin; cin=TRIS-cinnamic acid alkanolamide), (TBA)3 [MnMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]⋅3.5 ACN (TBA-MnMo6 -bzn), and (TBA)3 [MnMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]⋅2.5 ACN (TBA-MnMo6 -cin). To make these four compounds applicable in biological systems, an ion exchange was performed that gave the water-soluble (up to 80 mM) sodium salts Na3 [FeMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ] (Na-FeMo6 -bzn), Na3 [FeMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ] (Na-FeMo6 -cin), Na3 [MnMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ] (Na-MnMo6 -bzn), and Na3 [MnMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ] (Na-MnMo6 -cin). The hydrolytic stability of the sodium salts was examined by applying ESI-MS in the pH range of 4 to 9. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that human and bovine serum albumin (HSA and BSA) remain intact in solutions that contain up to 100 equivalents of the sodium salts over more than 4 d at 20 °C. Tryptophan (Trp) fluorescence quenching was applied to study the interactions between the sodium salts and HSA and BSA at pH 5.5 and 7.4. The quenching constants were extracted by using Stern-Volmer analysis, which suggested the formation of a 1:1 POM-protein complex in all samples. It is suggested that the aromatic hybrid POM approaches subdomain IIA of HSA and exhibits hydrophobic interactions with its hydrophobic tails, whereas the Anderson core is stabilized through electrostatic interactions with polar amino acid side chains from, for example, subdomain IB.
通过预官能化方案合成了四种以Fe(3+)或Mn(3+)作为中心杂原子的芳香族杂化安德森多金属氧酸盐，并通过单晶X射线衍射、傅里叶变换红外光谱（FTIR）、电喷雾电离质谱（ESI-MS）、核磁共振氢谱（1H NMR）和元素分析对其进行了表征。结构分析表明形成了(TBA)3 [FeMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]⋅3.5 ACN（TBA-FeMo6 -bzn；TBA = 四丁基铵，ACN = 乙腈，bzn = 三（羟甲基）氨基甲烷 - 苯甲酸链烷醇酰胺，TRISR = (HOCH2 )3 CR））、(TBA)3 [FeMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]⋅2.5 ACN（TBA-FeMo6 -cin；cin = 三（羟甲基）氨基甲烷 - 肉桂酸链烷醇酰胺）、(TBA)3 [MnMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]⋅3.5 ACN（TBA-MnMo6 -bzn）和(TBA)3 [MnMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]⋅2.5 ACN（TBA-MnMo6 -cin）。为使这四种化合物适用于生物体系，进行了离子交换，得到了水溶性（高达80 mM）的钠盐Na3 [FeMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]（Na-FeMo6 -bzn）、Na3 [FeMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]（Na-FeMo6 -cin）、Na3 [MnMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]（Na-MnMo6 -bzn）和Na3 [MnMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]（Na-MnMo6 -cin）。通过在pH值为4至9的范围内应用ESI-MS来检测钠盐的水解稳定性。十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳（SDS-PAGE）表明，在20°C下，人血清白蛋白和牛血清白蛋白（HSA和BSA）在含有高达100当量钠盐的溶液中超过4天仍保持完整。应用色氨酸（Trp）荧光猝灭来研究在pH 5.5和7.4下钠盐与HSA和BSA之间的相互作用。通过Stern-Volmer分析提取猝灭常数，这表明在所有样品中均形成了1:1的多金属氧酸盐 - 蛋白质复合物。研究表明，芳香族杂化多金属氧酸盐接近HSA的IIA亚结构域，并与其疏水尾部表现出疏水相互作用，而安德森核心则通过与例如IB亚结构域的极性氨基酸侧链的静电相互作用得以稳定。
