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由于金属离子包括铜离子对人体的重要性,报道了一种含单个色氨酸的新型多肽分子(WDAHSS),证明利用这种分子可以通过荧光光谱测量的方法实现铜离子灵敏检测。WDAHSS的荧光由其包含的色氨酸残基的本征荧光贡献,易被铜离子猝灭。通过分析铜离子在不同pH值条件下与WDAHSS作用的荧光光谱并与单个色氨酸分子的光谱相比较,详细研究了铜离子猝灭WDAHSS荧光的机理。研究表明,WDAHSS结构中的组氨酸通过金属配位与铜离子作用,并联合肽键形成稳固的四方形平面结构,螯合铜离子,致使色氨酸残基发生荧光猝灭。同时详细讨论了不同pH值环境对WDAHSS荧光光谱的影响。通过荧光光谱测量和数值拟合,推测了WDAHSS和铜离子的结合常数。为了增强WDAHSS抗pH干扰的能力,特意对其氨基端乙酰化,在生理pH值范围内稳定了其荧光发射。此外,WDAHSS也采用了一些特殊设计的结构,很好地增强了它对铜离子灵敏探测的特异选择性和生物相容性。对WDAHSS的进一步研究有望用于生物体内或细胞内荧光成像检测。
Due to the importance of metal ions, including copper ions, to human beings, a novel tryptophan-containing peptide (WDAHSS) has been reported to demonstrate the sensitive detection of copper ions by fluorescence spectrometry. The fluorescence of WDAHSS contributes to the intrinsic fluorescence of the tryptophan residues it contains and is easily quenched by copper ions. By analyzing the fluorescence spectra of copper ions interacting with WDAHSS under different pH values and comparing with the spectra of single tryptophan molecules, the mechanism of copper ions quenching WDAHSS fluorescence has been studied in detail. The results showed that the histidine in WDAHSS structure interacts with copper ions through metal coordination and combines with peptide bond to form a stable tetragonal planar structure, chelating copper ions, resulting in fluorescence quenching of tryptophan residues. The effects of different pH values on the fluorescence spectra of WDAHSS were also discussed in detail. The binding constants of WDAHSS and copper ions were deduced by fluorescence spectroscopy and numerical fitting. In order to enhance the ability of WDAHSS to resist pH interference, its amino-terminal acetylation was deliberately stabilized, and its fluorescence emission was stabilized at physiological pH range. In addition, WDAHSS also incorporates a number of specially designed structures that enhance its specific selectivity and biocompatibility for the sensitive detection of copper ions. Further studies of WDAHSS are expected to be used for in vivo or intracellular fluorescence imaging assays.