Department of Industrial Chemistry "Toso Montanari", University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy.
Dalton Trans. 2018 Jul 17;47(28):9400-9410. doi: 10.1039/c8dt02052c.
Within the general framework of our past and current studies dealing with the investigation of the photophysical properties and the biological behavior of the family of tetrazolato and tetrazole Re(i) complexes, we have endeavored to investigate their potential in the luminescent staining of proteins purified by acrylamide gel electrophoresis. With the aim to provide the first examples of luminescent Re(i) complexes to be exploited for this specific purpose, we have designed and prepared four new Re(i)-based species with the general formula fac-[Re(CO)3(N^N)(Tph)]2-/0, where Tph is the 5-(phenyl)tetrazolato anion and N^N is in turn represented by bathophenanthroline disulfonate (BPS), bathocuproine disulfonate (BCS) or by the SO3- free bathocuproine (BC). In this latter case, the neutral complex fac-[Re(CO)3(BC)(Tph)] served as a model species for the characterization of the former disulfonate complexes. Its cationic analogue fac-[Re(CO)3(BC)(Tph-Me)]+ was also prepared by a straightforward methylation reaction. All complexes displayed bright phosphorescence in organic media and, relative to their water solubility, the dianionic species fac-[Re(CO)3(BPS)(Tph)]2- and fac-[Re(CO)3(BCS)(Tph)]2- were also highly emissive in aqueous solution. The sulfonate groups played a key role in promoting and significantly enhancing the luminescent staining performances of both the Re(i) complexes fac-[Re(CO)3(BPS)(Tph)]2- and fac-[Re(CO)3(BCS)(Tph)]2- for proteins. Highlighting a response superior to that of Coomassie Blue and comparable to the one obtained by the well-known silver staining method, these dianionic Re(i)-complexes could efficiently detect up to 50 ng of pure Bovine Serum Albumin (BSA), as well as all proteins found in a Standard Protein Marker mix and from a total protein extract. A lower but still good response for luminescent protein staining was surprisingly obtained by employing the -SO3- free neutral and cationic complexes fac-[Re(CO)3(BC)(Tph)] and fac-[Re(CO)3(BC)(Tph-Me)]+, respectively. These preliminary results open up new possibilities for the further widening of the use of Re(i)-based complexes as luminescent protein staining agents.
在我们过去和目前研究的一般框架内，涉及到四唑和三唑 Re(i)配合物的光物理性质和生物行为的研究，我们致力于研究它们在丙烯酰胺凝胶电泳纯化的蛋白质的荧光染色中的潜在应用。为了提供第一个用于此特定目的的发光 Re(i)配合物的例子，我们设计并制备了四个具有通式 fac-[Re(CO)3(N^N)(Tph)]2-/0 的新型 Re(i)基物质，其中 Tph 是 5-(苯基)四唑阴离子，N^N 依次由苯并菲二磺酸盐 (BPS)、苯并菲二磺酸盐 (BCS) 或无 SO3-的苯并菲 (BC) 表示。在后一种情况下，中性配合物 fac-[Re(CO)3(BC)(Tph)]被用作前两个二磺酸盐配合物的特征化模型物质。其阳离子类似物 fac-[Re(CO)3(BC)(Tph-Me)]+也通过简单的甲基化反应制备。所有配合物在有机介质中均显示出明亮的磷光，相对于其水溶性，二阴离子配合物 fac-[Re(CO)3(BPS)(Tph)]2-和 fac-[Re(CO)3(BCS)(Tph)]2-在水溶液中也具有高度发光性。磺酸盐基团在促进和显著增强 Re(i)配合物 fac-[Re(CO)3(BPS)(Tph)]2-和 fac-[Re(CO)3(BCS)(Tph)]2-的蛋白质荧光染色性能方面发挥了关键作用。这些二阴离子 Re(i)-配合物的响应比考马斯蓝亮，与著名的银染色方法的响应相当，可以有效地检测多达 50 ng 的纯牛血清白蛋白 (BSA)，以及标准蛋白质标记混合物和总蛋白质提取物中的所有蛋白质。令人惊讶的是，通过使用无 -SO3-的中性和阳离子配合物 fac-[Re(CO)3(BC)(Tph)]和 fac-[Re(CO)3(BC)(Tph-Me)]+，分别获得了对荧光蛋白质染色的较低但仍良好的响应。这些初步结果为进一步拓宽 Re(i)基配合物作为发光蛋白质染色剂的应用提供了新的可能性。
