Vibrational and electronic circular dichroism study of bile pigments: Complexes of bilirubin and biliverdin with metals
Vibrational and electronic circular dichroism study of bile pigments: Complexes of bilirubin and biliverdin with metals
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DOI：
10.1016/j.ab.2009.05.040
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发表时间：
2009-09-01
影响因子：
2.9
通讯作者：
Urbanova, Marie
中科院分区：
文献类型：
--
作者：
Goncharova, Iryna;Urbanova, Marie
通过电子圆二色性 (ECD) 和振动圆二色性 (VCD) 研究了胆红素 (BR) 和胆绿素 (BV) 与生物和有毒金属（Mn、Cu、Cd、Co、Fe、Ni、Zn 和 Ag）的络合。选择水中的聚-L-赖氨酸和β-环糊精作为能够识别具有确定的M-螺旋性的颜料的单一立体构象的基质。这种系统允许使用手性光学方法跟踪由颜料与金属在 pH 10-11 的水溶液中络合引起的结构变化，这种方法本质上对空间结构敏感。这些和其他光谱技术表明，BV 和 BR 与 Cd、Cu 和 Zn 形成单体配合物，并与 Mn 形成二聚配合物。与 Fe、Ni、Co 和 Ag 的配合物的稳定性明显较低。对于除 Zn 之外的任何所研究金属的螯合物，络合 BV 的 ECD 和 VCD 模式的符号均不会改变，这一例外情况可根据 BV 与 Zn 螯合物中相反螺旋性的表现来解释。就 FIR 而言，络合后观察到的 ECD 信号反转以及 VCD 光谱分析表明，分子发生了扁平化，即吡啶酮发色团之间的角度增加，而螺旋性没有反转。这种手性立体选择性在锌螯合物的情况下是非常特异的，我们结合胆汁色素对需要锌的酶的特异性抑制进行了讨论。 (c) 2009 Elsevier Inc. 保留所有权利。
Complexation of bilirubin (BR) and biliverdin (BV) with biogenic and toxic metals (Mn, Cu, Cd, Co, Fe, Ni, Zn. and Ag) has been studied by means of electronic circular dichroism (ECD) and vibrational circular dichroism (VCD). Poly-L-lysine and beta-cyclodextrin in water were chosen as matrices capable of recognizing the single stereoconformer of the pigments with defined M-helicity. Such systems allow structural changes caused by complexation of pigments with metals in aqueous solution at pH 10-11 to be followed using chiroptical methods, which are intrinsically sensitive to spatial structure. These and other spectroscopic techniques have revealed that BV and BR form monomeric complexes with Cd, Cu, and Zn and dimeric complexes with Mn. The stabilities of the complexes with Fe, Ni, Co, and Ag are remarkably lower. The sign of the ECD and VCD patterns of the complexed BV does not change for the chelates of any of the studied metals other than Zn, this exception being interpreted in terms of manifestation of the opposite helicity of BV in its chelate with Zn. In the case of FIR, the observed inversion of ECD signal after complexation, together with the analysis of VCD spectra, reveals that a flattening of the molecule takes place, i.e., an increase in the angle between the pyrrinone chromophores without an inversion of helicity. This chiral stereoselectivity, which is very specific in the case of the Zn chelates, is discussed in connection with the specific inhibition of Zn-required enzymes by bile pigments. (c) 2009 Elsevier Inc. All rights reserved.