A spiropyran-based ensemble for visual recognition and quantification of cysteine and homocysteine at physiological levels
A spiropyran-based ensemble for visual recognition and quantification of cysteine and homocysteine at physiological levels
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DOI：
10.1002/anie.200600112
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发表时间：
2006-01-01
影响因子：
16.6
通讯作者：
Mo, Tian
中科院分区：
文献类型：
--
作者：
Shao, Na;Jin, Jian Yu;Mo, Tian
螺吡喃和螺恶嗪属于光致变色化合物中最迷人的家族之一;它们在光、热或化学刺激下在无色螺环形式和有色汞之间进行可逆的结构异构化。[1]在有机溶剂中，螺吡喃转化为汞可以通过金属离子与连接在8位的另一个螯合官能团的协同连接的络合来诱导。[2]迄今为止，已经设计了许多这样的螺吡喃受体，并广泛应用于过渡金属和碱金属离子的光学检测。[3]然而，需要指出的是，尽管有大量的报道，螺吡喃结构很少用于识别阴离子或小的有机分子，如生物学上重要的氨基酸。Sunamoto等人早期证明，开放的mercury的两性离子特征应该使其能够通过静电相互作用与极性氨基酸分子结合;这种方法被用于氨基酸跨双层和膜的光控转移。[4]后来，Inouye等人设计了一种能够在非羟基有机溶剂中通过形成三氢键结合鸟苷衍生物的螺吡啶并吡喃。[5]然而，能够有效识别和定量水溶液中氨基酸的新螺吡喃和螺恶嗪探针的开发仍然是一个挑战。[1b]在20种氨基酸中，含巯基的氨基酸在生物系统中起着至关重要的作用。例如，半胱氨酸（Cys）、同型半胱氨酸（Hcy）和谷胱甘肽（GSH）已被证明与各种人类疾病有关。[6]目前，针对含巯基氨基酸和多肽的比色和荧光探针种类繁多，极具应用价值。大多数报道的方法是基于氧化还原化学或标记与生色团或荧光团和分离技术的组合。[7]最近，Strongin等人以及其他几个人在开发Cys和Hcy的高选择性探针以及基于探针分子与分析物之间的共价相互作用的硫醇定量酶测定方面取得了开创性进展，[8，9]其可用于直接测定体液中的氨基酸含量和酶活性。此外，Kim等人最近还开发了一种Cys的传感系综，该系综基于分析物与显色指示剂竞争金属受体。[10]该方法对Cys的选择性优于其他氨基酸，包括Hcy。尽管已经开发了许多反应和各种技术用于测定Cys和Hcy，[7-10]但在选择性、灵敏度和性能方面仍有很大的改进空间。在这里，我们提出了一种新的策略，有效地识别和测定半胱氨酸和同型半胱氨酸在中性水溶液中使用螺吡喃。在我们提出的方法中，游离螺吡喃与氨基酸的相互作用相对较弱，但螺吡喃分子可以结合金属离子，金属离子可以与氨基酸配体相互作用。因此，预期金属离子通过协同金属-配体相互作用与螺吡喃和氨基酸分子结合。如果这三种组分一起存在，则该方法的选择性基本上由金属中心和氨基酸之间的结合亲和力以及分析物的相对大小决定。在这种情况下，我们已经表明，在Cu ~（2+）或Hg ~（2+）离子的存在下，螺吡喃与半胱氨酸或同型半胱氨酸的相互作用。
Spiropyrans and spirooxazines belong to one of the most fascinating families of photochromic compounds; they undergo reversible structural isomerization between a colorless spiro form and a colored merocyanine upon either light, heat, or chemical stimulus.[1] In organic solvents the conversion of spiropyran into merocyanine can be induced by complexation of a metal ion with cooperative ligation of another chelating functionality attached at the 8о-position.[2] Up to now, a number of such spiropyran receptors have been designed and widely applied for the optical detection of transition-metal and alkali-metal ions.[3] It should be pointed out, however, that despite the large number of reports, spiropyran structures have rarely been used to recognize anions or small organic molecules such as biologically important amino acids. Sunamoto et al. demonstrated early on that the zwitterionic feature of the opened merocyanine should enable it to bind with a polar amino acid molecule through electrostatic interactions; this approach was utilized for the photocontrolled transfer of amino acids across bilayers and membranes.[4] Later, Inouye et al. designed a spiropyridopyran capable of binding guanosine derivatives in nonhydroxylic organic solvents by forming triple hydrogen bonds.[5] And yet, development of new spiropyrans and spirooxazines probes capable of efficient recognition and quantification of amino acids in aqueous solution remains a challenge.[1b]Of the twenty amino acids used as building blocks for proteins, the thiol-containing amino acids play crucial roles in biological systems. For example, cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) have been proven to be linked to various human diseases.[6] At present, a wide variety of colorimetric and fluorescent probes for thiol-containing amino acids and peptides are valuable. The majority of the reported methods are based on redox chemistry or labeling with chromophores or fluorophores and a combination of separation techniques.[7] Recently, Strongin et al. as well as several others have made pioneering advances in developing highly selective probes for Cys and Hcy, as well as a thiolquantification enzyme assay based on the covalent interaction between the probe molecule and the analyte,[8, 9] which could be used for the direct assay of the amino acid content and the enzyme activity in body fluids. In addition, a sensing ensemble for Cys was also recently developed by Kim et al. based on the analyte competing for a metal receptor with a chromogenic indicator.[10] The approach showed excellent selectivity for Cys over other amino acids including Hcy. Although many reactions and various techniques have been developed for assaying Cys and Hcy,[7–10] there is still plenty of room for improvement in term of selectivity, sensitivity, and performance with a new interaction mechanism. Here we present a new strategy for the efficient recognition and determination of Cys and Hcy in neutral aqueous solution using a spiropyran. In our proposed approach the interaction of the free spiropyran with an amino acid is comparatively weak, but the spiropyran molecule can bind a metal ion, which can interact with an amino acid ligand. The metal ion is thus expected to bind with both the spiropyran and the amino acid molecule through cooperative metal–ligand interactions. If the three components exist together, the selectivity of the approach is essentially determined by the binding affinity between the metal center and the amino acid, as well as the relative size of the analyte. In this context, we have shown that in the presence of Cu2+ or Hg2+ ions the interaction of the spiropyran with Cys or Hcy …